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format package

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R=r,rsc
DELTA=2871  (1712 added, 1118 deleted, 41 changed)
OCL=29222
CL=29704
This commit is contained in:
Robert Griesemer 2009-06-01 19:13:44 -07:00
parent 2494bcb4b1
commit d7acfc75cd
11 changed files with 1756 additions and 1157 deletions
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1
src/lib/Make.deps
View File

@ -10,6 +10,7 @@ exec.install: os.install strings.install
exvar.install: fmt.install http.install io.install log.install strconv.install sync.install
flag.install: fmt.install os.install strconv.install
fmt.install: io.install os.install reflect.install strconv.install utf8.install
format.install: container/vector.install flag.install fmt.install go/scanner.install go/token.install io.install os.install reflect.install runtime.install strconv.install strings.install
go/ast.install: go/token.install unicode.install utf8.install
go/doc.install: container/vector.install fmt.install go/ast.install go/token.install io.install once.install regexp.install sort.install strings.install template.install
go/parser.install: container/vector.install fmt.install go/ast.install go/scanner.install go/token.install io.install os.install

2
src/lib/Makefile
View File

@ -26,6 +26,7 @@ DIRS=\
exvar\
flag\
fmt\
format\
go/ast\
go/doc\
go/parser\
@ -73,6 +74,7 @@ TEST=\
exvar\
flag\
fmt\
format\
go/parser\
go/scanner\
hash/adler32\

76
src/lib/format/Makefile Normal file
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@ -0,0 +1,76 @@
# Copyright 2009 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
# DO NOT EDIT. Automatically generated by gobuild.
# gobuild -m >Makefile
D=
O_arm=5
O_amd64=6
O_386=8
OS=568vq
O=$(O_$(GOARCH))
GC=$(O)g -I_obj
CC=$(O)c -FVw
AS=$(O)a
AR=6ar
default: packages
clean:
rm -rf *.[$(OS)] *.a [$(OS)].out _obj
test: packages
gotest
coverage: packages
gotest
6cov -g `pwd` | grep -v '_test\.go:'
%.$O: %.go
$(GC) $*.go
%.$O: %.c
$(CC) $*.c
%.$O: %.s
$(AS) $*.s
O1=\
format.$O\
O2=\
parser.$O\
phases: a1 a2
_obj$D/format.a: phases
a1: $(O1)
$(AR) grc _obj$D/format.a format.$O
rm -f $(O1)
a2: $(O2)
$(AR) grc _obj$D/format.a parser.$O
rm -f $(O2)
newpkg: clean
mkdir -p _obj$D
$(AR) grc _obj$D/format.a
$(O1): newpkg
$(O2): a1
$(O3): a2
nuke: clean
rm -f $(GOROOT)/pkg$D/format.a
packages: _obj$D/format.a
install: packages
test -d $(GOROOT)/pkg && mkdir -p $(GOROOT)/pkg$D
cp _obj$D/format.a $(GOROOT)/pkg$D/format.a

786
src/lib/format/format.go Normal file
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@ -0,0 +1,786 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
/* The format package implements syntax-directed, type-driven formatting
of arbitrary data structures. Formatting a data structure consists of
two phases: first, a parser reads a format specification and builds a
"compiled" format. Then, the format can be applied repeatedly to
arbitrary values. Applying a format to a value evaluates to a []byte
containing the formatted value bytes, or nil.
A format specification is a set of package declarations and format rules:
Format = [ Entry { ";" Entry } [ ";" ] ] .
Entry = PackageDecl | FormatRule .
(The syntax of a format specification is presented in the same EBNF
notation as used in the Go language specification. The syntax of white
space, comments, identifiers, and string literals is the same as in Go.)
A package declaration binds a package name (such as 'ast') to a
package import path (such as '"go/ast"'). Each package used (in
a type name, see below) must be declared once before use.
PackageDecl = PackageName ImportPath .
PackageName = identifier .
ImportPath = string .
A format rule binds a rule name to a format expression. A rule name
may be a type name or one of the special names 'default' or '/'.
A type name may be the name of a predeclared type (for example, 'int',
'float32', etc.), the package-qualified name of a user-defined type
(for example, 'ast.MapType'), or an identifier indicating the structure
of unnamed composite types ('array', 'chan', 'func', 'interface', 'map',
or 'ptr'). Each rule must have a unique name; rules can be declared in
any order.
FormatRule = RuleName "=" Expression .
RuleName = TypeName | "default" | "/" .
TypeName = [ PackageName "." ] identifier .
To format a value, the value's type name is used to select the format rule
(there is an override mechanism, see below). The format expression of the
selected rule specifies how the value is formatted. Each format expression,
when applied to a value, evaluates to a byte sequence or nil.
In its most general form, a format expression is a list of alternatives,
each of which is a sequence of operands:
Expression = [ Sequence ] { "|" [ Sequence ] } .
Sequence = Operand { Operand } .
The formatted result produced by an expression is the result of the first
alternative sequence that evaluates to a non-nil result; if there is no
such alternative, the expression evaluates to nil. The result produced by
an operand sequence is the concatenation of the results of its operands.
If any operand in the sequence evaluates to nil, the entire sequence
evaluates to nil.
There are five kinds of operands:
Operand = Literal | Field | Group | Option | Repetition .
Literals evaluate to themselves, with two substitutions. First,
%-formats expand in the manner of fmt.Printf, with the current value
passed as the parameter. Second, the current indentation (see below)
is inserted after every newline character.
Literal = string .
This table shows string literals applied to the value 42 and the
corresponding formatted result:
"foo" foo
"%x" 2a
"x = %d" x = 42
"%#x = %d" 0x2a = 42
A field operand is a field name optionally followed by an alternate
rule name. The field name may be an identifier or one of the special
names ^ or *.
Field = FieldName [ ":" RuleName ] .
FieldName = identifier | "^" | "*" .
If the field name is an identifier, the current value must be a struct,
and there must be a field with that name in the struct. The same lookup
rules apply as in the Go language (for instance, the name of an anonymous
field is the unqualified type name). The field name denotes the field
value in the struct. If the field is not found, formatting is aborted
and an error message is returned. (TODO consider changing the semantics
such that if a field is not found, it evaluates to nil).
The special name '^' denotes the current value. (TODO see if ^ can
change to @ or be eliminated).
The meaning of the special name '*' depends on the type of the current
value:
array, slice types array, slice element (inside {} only, see below)
interfaces value stored in interface
pointers value pointed to by pointer
(Implementation restriction: channel, function and map types are not
supported due to missing reflection support).
Fields are evaluated as follows: If the field value is nil, or an array
or slice element does not exist, the result is nil (see below for details
on array/slice elements). If the value is not nil the field value is
formatted (recursively) using the rule corresponding to its type name,
or the alternate rule name, if given.
The following example shows a complete format specification for a
struct 'myPackage.Point'. Assume the package
package myPackage // in directory myDir/myPackage
type Point struct {
name string;
x, y int;
}
Applying the format specification
myPackage "myDir/myPackage";
int = "%d";
hexInt = "0x%x";
string = "---%s---";
myPackage.Point = name "{" x ", " y:hexInt "}";
to the value myPackage.Point{"foo", 3, 15} results in
---foo---{3, 0xf}
Finally, an operand may be a grouped, optional, or repeated expression.
A grouped expression ("group") groups a more complex expression (body)
so that it can be used in place of a single operand:
Group = "(" [ Indentation ">>" ] Body ")" .
Indentation = Expression .
Body = Expression .
A group body may be prefixed by an indentation expression followed by '>>'.
The indentation expression is applied to the current value like any other
expression and the result, if not nil, is appended to the current indentation
during the evaluation of the body (see also formatting state, below).
An optional expression ("option") is enclosed in '[]' brackets.
Option = "[" Body "]" .
An option evaluates to its body, except that if the body evaluates to nil,
the option expression evaluates to an empty []byte. Thus an option's purpose
is to protect the expression containing the option from a nil operand.
A repeated expression ("repetition") is enclosed in '{}' braces.
Repetition = "{" Body [ "/" Separator ] "}" .
Separator = Expression .
A repeated expression is evaluated as follows: The body is evaluated
repeatedly and its results are concatenated until the body evaluates
to nil. The result of the repetition is the (possibly empty) concatenation,
but it is never nil. An implicit index is supplied for the evaluation of
the body: that index is used to address elements of arrays or slices. If
the corresponding elements do not exist, the field denoting the element
evaluates to nil (which in turn may terminate the repetition).
The body of a repetition may be followed by a '/' and a "separator"
expression. If the separator is present, it is invoked between repetitions
of the body.
The following example shows a complete format specification for formatting
a slice of unnamed type. Applying the specification
int = "%b";
array = { * / ", " }; // array is the type name for an unnamed slice
to the value '[]int{2, 3, 5, 7}' results in
10, 11, 101, 111
Default rule: If a format rule named 'default' is present, it is used for
formatting a value if no other rule was found. A common default rule is
default = "%v"
to provide default formatting for basic types without having to specify
a specific rule for each basic type.
Global separator rule: If a format rule named '/' is present, it is
invoked with the current value between literals. If the separator
expression evaluates to nil, it is ignored.
For instance, a global separator rule may be used to punctuate a sequence
of values with commas. The rules:
default = "%v";
/ = ", ";
will format an argument list by printing each one in its default format,
separated by a comma and a space.
*/
package format
import (
"container/vector";
"fmt";
"go/token";
"io";
"os";
"reflect";
"runtime";
"strconv";
"strings";
)
// ----------------------------------------------------------------------------
// Format representation
type State struct
// Custom formatters implement the Formatter function type.
// A formatter is invoked with the current formatting state, the
// value to format, and the rule name under which the formatter
// was installed (the same formatter function may be installed
// under different names). The formatter may access the current state
// to guide formatting and use State.Write to append to the state's
// output.
//
// A formatter must return a boolean value indicating if it evaluated
// to a non-nil value (true), or a nil value (false).
//
type Formatter func(state *State, value interface{}, ruleName string) bool
// A FormatterMap is a set of custom formatters.
// It maps a rule name to a formatter function.
//
type FormatterMap map [string] Formatter;
// A parsed format expression is built from the following nodes.
//
type (
expr interface {};
alternatives []expr; // x | y | z
sequence []expr; // x y z
literal [][]byte; // a list of string segments, possibly starting with '%'
field struct {
fieldName string; // including "^", "*"
ruleName string; // "" if no rule name specified
};
group struct {
indent, body expr; // (indent >> body)
};
option struct {
body expr; // [body]
};
repetition struct {
body, separator expr; // {body / separator}
};
custom struct {
ruleName string;
fun Formatter
};
)
// A Format is the result of parsing a format specification.
// The format may be applied repeatedly to format values.
//
type Format map [string] expr;
// ----------------------------------------------------------------------------
// Formatting
// An application-specific environment may be provided to Format.Apply;
// the environment is available inside custom formatters via State.Env().
// Environments must implement copying; the Copy method must return an
// complete copy of the receiver. This is necessary so that the formatter
// can save and restore an environment (in case of an absent expression).
//
// If the Environment doesn't change during formatting (this is under
// control of the custom formatters), the Copy function can simply return
// the receiver, and thus can be very light-weight.
//
type Environment interface {
Copy() Environment
}
// State represents the current formatting state.
// It is provided as argument to custom formatters.
//
type State struct {
fmt Format; // format in use
env Environment; // user-supplied environment
errors chan os.Error; // not chan *Error (errors <- nil would be wrong!)
hasOutput bool; // true after the first literal has been written
indent io.ByteBuffer; // current indentation
output io.ByteBuffer; // format output
linePos token.Position; // position of line beginning (Column == 0)
default_ expr; // possibly nil
separator expr; // possibly nil
}
func newState(fmt Format, env Environment, errors chan os.Error) *State {
s := new(State);
s.fmt = fmt;
s.env = env;
s.errors = errors;
s.linePos = token.Position{Line: 1};
// if we have a default rule, cache it's expression for fast access
if x, found := fmt["default"]; found {
s.default_ = x;
}
// if we have a global separator rule, cache it's expression for fast access
if x, found := fmt["/"]; found {
s.separator = x;
}
return s;
}
// Env returns the environment passed to Format.Apply.
func (s *State) Env() interface{} {
return s.env;
}
// LinePos returns the position of the current line beginning
// in the state's output buffer. Line numbers start at 1.
//
func (s *State) LinePos() token.Position {
return s.linePos;
}
// Pos returns the position of the next byte to be written to the
// output buffer. Line numbers start at 1.
//
func (s *State) Pos() token.Position {
offs := s.output.Len();
return token.Position{Line: s.linePos.Line, Column: offs - s.linePos.Offset, Offset: offs};
}
// Write writes data to the output buffer, inserting the indentation
// string after each newline. It cannot return an error.
//
func (s *State) Write(data []byte) (int, os.Error) {
n := 0;
i0 := 0;
for i, ch := range data {
if ch == '\n' {
// write text segment and indentation
n1, _ := s.output.Write(data[i0 : i+1]);
n2, _ := s.output.Write(s.indent.Data());
n += n1 + n2;
i0 = i + 1;
s.linePos.Offset = s.output.Len();
s.linePos.Line++;
}
}
n3, _ := s.output.Write(data[i0 : len(data)]);
return n + n3, nil;
}
type checkpoint struct {
env Environment;
hasOutput bool;
outputLen int;
linePos token.Position;
}
func (s *State) save() checkpoint {
saved := checkpoint{nil, s.hasOutput, s.output.Len(), s.linePos};
if s.env != nil {
saved.env = s.env.Copy();
}
return saved;
}
func (s *State) restore(m checkpoint) {
s.env = m.env;
s.output.Truncate(m.outputLen);
}
func (s *State) error(msg string) {
s.errors <- os.NewError(msg);
runtime.Goexit();
}
// getField searches in val, which must be a struct, for a field
// with the given name. It returns the value and the embedded depth
// where it was found.
//
func getField(val reflect.Value, fieldname string) (reflect.Value, int) {
// do we have a struct in the first place?
if val.Kind() != reflect.StructKind {
return nil, 0;
}
sval, styp := val.(reflect.StructValue), val.Type().(reflect.StructType);
// look for field at the top level
for i := 0; i < styp.Len(); i++ {
name, typ, tag, offset := styp.Field(i);
if name == fieldname || name == "" && strings.HasSuffix(typ.Name(), "." + fieldname) /* anonymous field */ {
return sval.Field(i), 0;
}
}
// look for field in anonymous fields
var field reflect.Value;
level := 1000; // infinity (no struct has that many levels)
for i := 0; i < styp.Len(); i++ {
name, typ, tag, offset := styp.Field(i);
if name == "" {
f, l := getField(sval.Field(i), fieldname);
// keep the most shallow field
if f != nil {
switch {
case l < level:
field, level = f, l;
case l == level:
// more than one field at the same level,
// possibly an error unless there is a more
// shallow field found later
field = nil;
}
}
}
}
return field, level + 1;
}
// TODO At the moment, unnamed types are simply mapped to the default
// names below. For instance, all unnamed arrays are mapped to
// 'array' which is not really sufficient. Eventually one may want
// to be able to specify rules for say an unnamed slice of T.
//
var defaultNames = map[int]string {
reflect.ArrayKind: "array",
reflect.BoolKind: "bool",
reflect.ChanKind: "chan",
reflect.DotDotDotKind: "ellipsis",
reflect.FloatKind: "float",
reflect.Float32Kind: "float32",
reflect.Float64Kind: "float64",
reflect.FuncKind: "func",
reflect.IntKind: "int",
reflect.Int16Kind: "int16",
reflect.Int32Kind: "int32",
reflect.Int64Kind: "int64",
reflect.Int8Kind: "int8",
reflect.InterfaceKind: "interface",
reflect.MapKind: "map",
reflect.PtrKind: "ptr",
reflect.StringKind: "string",
reflect.StructKind: "struct",
reflect.UintKind: "uint",
reflect.Uint16Kind: "uint16",
reflect.Uint32Kind: "uint32",
reflect.Uint64Kind: "uint64",
reflect.Uint8Kind: "uint8",
reflect.UintptrKind: "uintptr",
}
func typename(value reflect.Value) string {
name := value.Type().Name();
if name == "" {
if defaultName, found := defaultNames[value.Kind()]; found {
name = defaultName;
}
}
return name;
}
func (s *State) getFormat(name string) expr {
if fexpr, found := s.fmt[name]; found {
return fexpr;
}
if s.default_ != nil {
return s.default_;
}
s.error(fmt.Sprintf("no format rule for type: '%s'", name));
return nil;
}
// eval applies a format expression fexpr to a value. If the expression
// evaluates internally to a non-nil []byte, that slice is appended to
// the state's output buffer and eval returns true. Otherwise, eval
// returns false and the state remains unchanged.
//
func (s *State) eval(fexpr expr, value reflect.Value, index int) bool {
// an empty format expression always evaluates
// to a non-nil (but empty) []byte
if fexpr == nil {
return true;
}
switch t := fexpr.(type) {
case alternatives:
// append the result of the first alternative that evaluates to
// a non-nil []byte to the state's output
mark := s.save();
for _, x := range t {
if s.eval(x, value, index) {
return true;
}
s.restore(mark);
}
return false;
case sequence:
// append the result of all operands to the state's output
// unless a nil result is encountered
mark := s.save();
for _, x := range t {
if !s.eval(x, value, index) {
s.restore(mark);
return false;
}
}
return true;
case literal:
// write separator, if any
if s.hasOutput {
// not the first literal
if s.separator != nil {
sep := s.separator; // save current separator
s.separator = nil; // and disable it (avoid recursion)
mark := s.save();
if !s.eval(sep, value, index) {
s.restore(mark);
}
s.separator = sep; // enable it again
}
}
s.hasOutput = true;
// write literal segments
for _, lit := range t {
if lit[0] == '%' && len(lit) > 1 {
// segment contains a %-format at the beginning
if lit[1] == '%' {
// "%%" is printed as a single "%"
s.Write(lit[1 : len(lit)]);
} else {
// use s instead of s.output to get indentation right
fmt.Fprintf(s, string(lit), value.Interface());
}
} else {
// segment contains no %-formats
s.Write(lit);
}
}
return true; // a literal never evaluates to nil
case *field:
// determine field value
switch t.fieldName {
case "^":
// field value is current value
case "*":
// indirection: operation is type-specific
switch v := value.(type) {
case reflect.ArrayValue:
if v.IsNil() || v.Len() <= index {
return false;
}
value = v.Elem(index);
case reflect.MapValue:
s.error("reflection support for maps incomplete");
case reflect.PtrValue:
if v.IsNil() {
return false;
}
value = v.Sub();
case reflect.InterfaceValue:
if v.IsNil() {
return false;
}
value = v.Value();
case reflect.ChanValue:
s.error("reflection support for chans incomplete");
case reflect.FuncValue:
s.error("reflection support for funcs incomplete");
default:
s.error(fmt.Sprintf("error: * does not apply to `%s`", value.Type().Name()));
}
default:
// value is value of named field
field, _ := getField(value, t.fieldName);
if field == nil {
// TODO consider just returning false in this case
s.error(fmt.Sprintf("error: no field `%s` in `%s`", t.fieldName, value.Type().Name()));
}
value = field;
}
// determine rule
ruleName := t.ruleName;
if ruleName == "" {
// no alternate rule name, value type determines rule
ruleName = typename(value)
}
fexpr = s.getFormat(ruleName);
mark := s.save();
if !s.eval(fexpr, value, index) {
s.restore(mark);
return false;
}
return true;
case *group:
// remember current indentation
indentLen := s.indent.Len();
// update current indentation
mark := s.save();
s.eval(t.indent, value, index);
// if the indentation evaluates to nil, the state's output buffer
// didn't change - either way it's ok to append the difference to
// the current identation
s.indent.Write(s.output.Data()[mark.outputLen : s.output.Len()]);
s.restore(mark);
// format group body
mark = s.save();
b := true;
if !s.eval(t.body, value, index) {
s.restore(mark);
b = false;
}
// reset indentation
s.indent.Truncate(indentLen);
return b;
case *option:
// evaluate the body and append the result to the state's output
// buffer unless the result is nil
mark := s.save();
if !s.eval(t.body, value, 0) { // TODO is 0 index correct?
s.restore(mark);
}
return true; // an option never evaluates to nil
case *repetition:
// evaluate the body and append the result to the state's output
// buffer until a result is nil
for i := 0; ; i++ {
mark := s.save();
// write separator, if any
if i > 0 && t.separator != nil {
// nil result from separator is ignored
mark := s.save();
if !s.eval(t.separator, value, i) {
s.restore(mark);
}
}
if !s.eval(t.body, value, i) {
s.restore(mark);
break;
}
}
return true; // a repetition never evaluates to nil
case *custom:
// invoke the custom formatter to obtain the result
mark := s.save();
if !t.fun(s, value.Interface(), t.ruleName) {
s.restore(mark);
return false;
}
return true;
}
panic("unreachable");
return false;
}
// Eval formats each argument according to the format
// f and returns the resulting []byte and os.Error. If
// an error occured, the []byte contains the partially
// formatted result. An environment env may be passed
// in which is available in custom formatters through
// the state parameter.
//
func (f Format) Eval(env Environment, args ...) ([]byte, os.Error) {
errors := make(chan os.Error);
s := newState(f, env, errors);
go func() {
value := reflect.NewValue(args).(reflect.StructValue);
for i := 0; i < value.Len(); i++ {
fld := value.Field(i);
mark := s.save();
if !s.eval(s.getFormat(typename(fld)), fld, 0) { // TODO is 0 index correct?
s.restore(mark);
}
}
errors <- nil; // no errors
}();
return s.output.Data(), <- errors;
}
// ----------------------------------------------------------------------------
// Convenience functions
// Fprint formats each argument according to the format f
// and writes to w. The result is the total number of bytes
// written and an os.Error, if any.
//
func (f Format) Fprint(w io.Writer, env Environment, args ...) (int, os.Error) {
data, err := f.Eval(env, args);
if err != nil {
// TODO should we print partial result in case of error?
return 0, err;
}
return w.Write(data);
}
// Print formats each argument according to the format f
// and writes to standard output. The result is the total
// number of bytes written and an os.Error, if any.
//
func (f Format) Print(args ...) (int, os.Error) {
return f.Fprint(os.Stdout, nil, args);
}
// Sprint formats each argument according to the format f
// and returns the resulting string. If an error occurs
// during formatting, the result string contains the
// partially formatted result followed by an error message.
//
func (f Format) Sprint(args ...) string {
var buf io.ByteBuffer;
n, err := f.Fprint(&buf, nil, args);
if err != nil {
fmt.Fprintf(&buf, "--- Sprint(%s) failed: %v", fmt.Sprint(args), err);
}
return string(buf.Data());
}

365
src/lib/format/format_test.go Normal file
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@ -0,0 +1,365 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package format
import (
"fmt";
"format";
"io";
"os";
"testing";
)
func parse(t *testing.T, form string, fmap format.FormatterMap) format.Format {
f, err := format.Parse(io.StringBytes(form), fmap);
if err != nil {
t.Errorf("Parse(%s): %v", err);
return nil;
}
return f;
}
func verify(t *testing.T, f format.Format, expected string, args ...) {
if f == nil {
return; // allow other tests to run
}
result := f.Sprint(args);
if result != expected {
t.Errorf(
"result : `%s`\nexpected: `%s`\n\n",
result, expected
)
}
}
func formatter(s *format.State, value interface{}, rule_name string) bool {
switch rule_name {
case "/":
fmt.Fprintf(s, "%d %d %d", s.Pos().Line, s.LinePos().Column, s.Pos().Column);
return true;
case "blank":
s.Write([]byte{' '});
return true;
case "int":
if value.(int) & 1 == 0 {
fmt.Fprint(s, "even ");
} else {
fmt.Fprint(s, "odd ");
}
return true;
case "nil":
return false;
}
panic("unreachable");
return false;
}
func TestCustomFormatters(t *testing.T) {
fmap0 := format.FormatterMap{ "/": formatter };
fmap1 := format.FormatterMap{ "int": formatter, "blank": formatter, "nil": formatter };
f := parse(t, `int=`, fmap0);
verify(t, f, ``, 1, 2, 3);
f = parse(t, `int="#"`, nil);
verify(t, f, `###`, 1, 2, 3);
f = parse(t, `int="#";string="%s"`, fmap0);
verify(t, f, "#1 0 1#1 0 7#1 0 13\n2 0 0foo2 0 8\n", 1, 2, 3, "\n", "foo", "\n");
f = parse(t, ``, fmap1);
verify(t, f, `even odd even odd `, 0, 1, 2, 3);
f = parse(t, `/ =^:blank; float="#"`, fmap1);
verify(t, f, `# # #`, 0.0, 1.0, 2.0);
f = parse(t, `float=^:nil`, fmap1);
verify(t, f, ``, 0.0, 1.0, 2.0);
// TODO needs more tests
}
// ----------------------------------------------------------------------------
// Formatting of basic and simple composite types
func check(t *testing.T, form, expected string, args ...) {
f := parse(t, form, nil);
result := f.Sprint(args);
if result != expected {
t.Errorf(
"format : %s\nresult : `%s`\nexpected: `%s`\n\n",
form, result, expected
)
}
}
func TestBasicTypes(t *testing.T) {
check(t, ``, ``);
check(t, `bool=":%v"`, `:true:false`, true, false);
check(t, `int="%b %d %o 0x%x"`, `101010 42 52 0x2a`, 42);
check(t, `int="%"`, `%`, 42);
check(t, `int="%%"`, `%`, 42);
check(t, `int="**%%**"`, `**%**`, 42);
check(t, `int="%%%%%%"`, `%%%`, 42);
check(t, `int="%%%d%%"`, `%42%`, 42);
const i = -42;
const is = `-42`;
check(t, `int ="%d"`, is, i);
check(t, `int8 ="%d"`, is, int8(i));
check(t, `int16="%d"`, is, int16(i));
check(t, `int32="%d"`, is, int32(i));
check(t, `int64="%d"`, is, int64(i));
const u = 42;
const us = `42`;
check(t, `uint ="%d"`, us, uint(u));
check(t, `uint8 ="%d"`, us, uint8(u));
check(t, `uint16="%d"`, us, uint16(u));
check(t, `uint32="%d"`, us, uint32(u));
check(t, `uint64="%d"`, us, uint64(u));
const f = 3.141592;
const fs = `3.141592`;
check(t, `float ="%g"`, fs, f);
check(t, `float32="%g"`, fs, float32(f));
check(t, `float64="%g"`, fs, float64(f));
}
func TestArrayTypes(t *testing.T) {
var a0 [10]int;
check(t, `array="array";`, `array`, a0);
a1 := [...]int{1, 2, 3};
check(t, `array="array";`, `array`, a1);
check(t, `array={*}; int="%d";`, `123`, a1);
check(t, `array={* / ", "}; int="%d";`, `1, 2, 3`, a1);
check(t, `array={* / *}; int="%d";`, `12233`, a1);
a2 := []interface{}{42, "foo", 3.14};
check(t, `array={* / ", "}; interface=*; string="bar"; default="%v";`, `42, bar, 3.14`, a2);
}
func TestChanTypes(t *testing.T) {
var c0 chan int;
check(t, `chan="chan"`, `chan`, c0);
c1 := make(chan int);
go func(){ c1 <- 42 }();
check(t, `chan="chan"`, `chan`, c1);
// check(t, `chan=*`, `42`, c1); // reflection support for chans incomplete
}
func TestFuncTypes(t *testing.T) {
var f0 func() int;
check(t, `func="func"`, `func`, f0);
f1 := func() int { return 42; };
check(t, `func="func"`, `func`, f1);
// check(t, `func=*`, `42`, f1); // reflection support for funcs incomplete
}
func TestInterfaceTypes(t *testing.T) {
var i0 interface{};
check(t, `interface="interface"`, `interface`, i0);
i0 = "foo";
check(t, `interface="interface"`, `interface`, i0);
check(t, `interface=*; string="%s"`, `foo`, i0);
}
func TestMapTypes(t *testing.T) {
var m0 map[string]int;
check(t, `map="map"`, `map`, m0);
m1 := map[string]int{};
check(t, `map="map"`, `map`, m1);
// check(t, `map=*`, ``, m1); // reflection support for maps incomplete
}
func TestPointerTypes(t *testing.T) {
var p0 *int;
check(t, `ptr="ptr"`, `ptr`, p0);
check(t, `ptr=*`, ``, p0);
check(t, `ptr=*|"nil"`, `nil`, p0);
x := 99991;
p1 := &x;
check(t, `ptr="ptr"`, `ptr`, p1);
check(t, `ptr=*; int="%d"`, `99991`, p1);
}
func TestDefaultRule(t *testing.T) {
check(t, `default="%v"`, `42foo3.14`, 42, "foo", 3.14);
check(t, `default="%v"; int="%x"`, `abcdef`, 10, 11, 12, 13, 14, 15);
check(t, `default="%v"; int="%x"`, `ab**ef`, 10, 11, "**", 14, 15);
check(t, `default="%x"; int=^:default`, `abcdef`, 10, 11, 12, 13, 14, 15);
}
func TestGlobalSeparatorRule(t *testing.T) {
check(t, `int="%d"; / ="-"`, `1-2-3-4`, 1, 2, 3, 4);
check(t, `int="%x%x"; / ="*"`, `aa*aa`, 10, 10);
}
// ----------------------------------------------------------------------------
// Formatting of a struct
type T1 struct {
a int;
}
const F1 =
`format "format";`
`int = "%d";`
`format.T1 = "<" a ">";`
func TestStruct1(t *testing.T) {
check(t, F1, "<42>", T1{42});
}
// ----------------------------------------------------------------------------
// Formatting of a struct with an optional field (ptr)
type T2 struct {
s string;
p *T1;
}
const F2a =
F1 +
`string = "%s";`
`ptr = *;`
`format.T2 = s ["-" p "-"];`
const F2b =
F1 +
`string = "%s";`
`ptr = *;`
`format.T2 = s ("-" p "-" | "empty");`;
func TestStruct2(t *testing.T) {
check(t, F2a, "foo", T2{"foo", nil});
check(t, F2a, "bar-<17>-", T2{"bar", &T1{17}});
check(t, F2b, "fooempty", T2{"foo", nil});
}
// ----------------------------------------------------------------------------
// Formatting of a struct with a repetitive field (slice)
type T3 struct {
s string;
a []int;
}
const F3a =
`format "format";`
`default = "%v";`
`array = *;`
`format.T3 = s {" " a a / ","};`
const F3b =
`format "format";`
`int = "%d";`
`string = "%s";`
`array = *;`
`nil = ;`
`empty = *:nil;`
`format.T3 = s [a:empty ": " {a / "-"}]`
func TestStruct3(t *testing.T) {
check(t, F3a, "foo", T3{"foo", nil});
check(t, F3a, "foo 00, 11, 22", T3{"foo", []int{0, 1, 2}});
check(t, F3b, "bar", T3{"bar", nil});
check(t, F3b, "bal: 2-3-5", T3{"bal", []int{2, 3, 5}});
}
// ----------------------------------------------------------------------------
// Formatting of a struct with alternative field
type T4 struct {
x *int;
a []int;
}
const F4a =
`format "format";`
`int = "%d";`
`ptr = *;`
`array = *;`
`nil = ;`
`empty = *:nil;`
`format.T4 = "<" (x:empty x | "-") ">" `
const F4b =
`format "format";`
`int = "%d";`
`ptr = *;`
`array = *;`
`nil = ;`
`empty = *:nil;`
`format.T4 = "<" (a:empty {a / ", "} | "-") ">" `
func TestStruct4(t *testing.T) {
x := 7;
check(t, F4a, "<->", T4{nil, nil});
check(t, F4a, "<7>", T4{&x, nil});
check(t, F4b, "<->", T4{nil, nil});
check(t, F4b, "<2, 3, 7>", T4{nil, []int{2, 3, 7}});
}
// ----------------------------------------------------------------------------
// Formatting a struct (documentation example)
type Point struct {
name string;
x, y int;
}
const FPoint =
`format "format";`
`int = "%d";`
`hexInt = "0x%x";`
`string = "---%s---";`
`format.Point = name "{" x ", " y:hexInt "}";`
func TestStructPoint(t *testing.T) {
p := Point{"foo", 3, 15};
check(t, FPoint, "---foo---{3, 0xf}", p);
}
// ----------------------------------------------------------------------------
// Formatting a slice (documentation example)
const FSlice =
`int = "%b";`
`array = { * / ", " }`
func TestSlice(t *testing.T) {
check(t, FSlice, "10, 11, 101, 111", []int{2, 3, 5, 7});
}
// TODO add more tests

445
src/lib/format/parser.go Normal file
View File

@ -0,0 +1,445 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package format
import (
"container/vector";
"fmt";
"format";
"go/scanner";
"go/token";
"io";
"os";
"strconv";
"strings";
)
// ----------------------------------------------------------------------------
// Error handling
// Error describes an individual error. The position Pos, if valid,
// indicates the format source position the error relates to. The
// error is specified with the Msg string.
//
type Error struct {
Pos token.Position;
Msg string;
}
func (e *Error) String() string {
pos := "";
if e.Pos.IsValid() {
pos = fmt.Sprintf("%d:%d: ", e.Pos.Line, e.Pos.Column);
}
return pos + e.Msg;
}
// An ErrorList is a list of errors encountered during parsing.
type ErrorList []*Error
// ErrorList implements SortInterface and the os.Error interface.
func (p ErrorList) Len() int { return len(p); }
func (p ErrorList) Swap(i, j int) { p[i], p[j] = p[j], p[i]; }
func (p ErrorList) Less(i, j int) bool { return p[i].Pos.Offset < p[j].Pos.Offset; }
func (p ErrorList) String() string {
switch len(p) {
case 0: return "unspecified error";
case 1: return p[0].String();
}
return fmt.Sprintf("%s (and %d more errors)", p[0].String(), len(p) - 1);
}
// ----------------------------------------------------------------------------
// Parsing
type parser struct {
errors vector.Vector;
scanner scanner.Scanner;
pos token.Position; // token position
tok token.Token; // one token look-ahead
lit []byte; // token literal
packs map [string] string; // PackageName -> ImportPath
rules map [string] expr; // RuleName -> Expression
}
func (p *parser) next() {
p.pos, p.tok, p.lit = p.scanner.Scan();
switch p.tok {
case token.CHAN, token.FUNC, token.INTERFACE, token.MAP, token.STRUCT:
// Go keywords for composite types are type names
// returned by reflect. Accept them as identifiers.
p.tok = token.IDENT; // p.lit is already set correctly
}
}
func (p *parser) init(src []byte) {
p.errors.Init(0);
p.scanner.Init(src, p, 0);
p.next(); // initializes pos, tok, lit
p.packs = make(map [string] string);
p.rules = make(map [string] expr);
}
// The parser implements scanner.Error.
func (p *parser) Error(pos token.Position, msg string) {
// Don't collect errors that are on the same line as the previous error
// in the hope to reduce the number of spurious errors due to incorrect
// parser synchronization.
if p.errors.Len() == 0 || p.errors.Last().(*Error).Pos.Line != pos.Line {
p.errors.Push(&Error{pos, msg});
}
}
func (p *parser) errorExpected(pos token.Position, msg string) {
msg = "expected " + msg;
if pos.Offset == p.pos.Offset {
// the error happened at the current position;
// make the error message more specific
msg += ", found '" + p.tok.String() + "'";
if p.tok.IsLiteral() {
msg += " " + string(p.lit);
}
}
p.Error(pos, msg);
}
func (p *parser) expect(tok token.Token) token.Position {
pos := p.pos;
if p.tok != tok {
p.errorExpected(pos, "'" + tok.String() + "'");
}
p.next(); // make progress in any case
return pos;
}
func (p *parser) parseIdentifier() string {
name := string(p.lit);
p.expect(token.IDENT);
return name;
}
func (p *parser) parseTypeName() (string, bool) {
pos := p.pos;
name, isIdent := p.parseIdentifier(), true;
if p.tok == token.PERIOD {
// got a package name, lookup package
if importPath, found := p.packs[name]; found {
name = importPath;
} else {
p.Error(pos, "package not declared: " + name);
}
p.next();
name, isIdent = name + "." + p.parseIdentifier(), false;
}
return name, isIdent;
}
// Parses a rule name and returns it. If the rule name is
// a package-qualified type name, the package name is resolved.
// The 2nd result value is true iff the rule name consists of a
// single identifier only (and thus could be a package name).
//
func (p *parser) parseRuleName() (string, bool) {
name, isIdent := "", false;
switch p.tok {
case token.IDENT:
name, isIdent = p.parseTypeName();
case token.DEFAULT:
name = "default";
p.next();
case token.QUO:
name = "/";
p.next();
default:
p.errorExpected(p.pos, "rule name");
p.next(); // make progress in any case
}
return name, isIdent;
}
func (p *parser) parseString() string {
s := "";
if p.tok == token.STRING {
var err os.Error;
s, err = strconv.Unquote(string(p.lit));
// Unquote may fail with an error, but only if the scanner found
// an illegal string in the first place. In this case the error
// has already been reported.
p.next();
return s;
} else {
p.expect(token.STRING);
}
return s;
}
func (p *parser) parseLiteral() literal {
s := io.StringBytes(p.parseString());
// A string literal may contain %-format specifiers. To simplify
// and speed up printing of the literal, split it into segments
// that start with "%" possibly followed by a last segment that
// starts with some other character.
var list vector.Vector;
list.Init(0);
i0 := 0;
for i := 0; i < len(s); i++ {
if s[i] == '%' && i+1 < len(s) {
// the next segment starts with a % format
if i0 < i {
// the current segment is not empty, split it off
list.Push(s[i0 : i]);
i0 = i;
}
i++; // skip %; let loop skip over char after %
}
}
// the final segment may start with any character
// (it is empty iff the string is empty)
list.Push(s[i0 : len(s)]);
// convert list into a literal
lit := make(literal, list.Len());
for i := 0; i < list.Len(); i++ {
lit[i] = list.At(i).([]byte);
}
return lit;
}
func (p *parser) parseField() expr {
var fname string;
switch p.tok {
case token.XOR:
fname = "^";
p.next();
case token.MUL:
fname = "*";
p.next();
case token.IDENT:
fname = p.parseIdentifier();
default:
return nil;
}
var ruleName string;
if p.tok == token.COLON {
p.next();
var _ bool;
ruleName, _ = p.parseRuleName();
}
return &field{fname, ruleName};
}
func (p *parser) parseExpression() expr
func (p *parser) parseOperand() (x expr) {
switch p.tok {
case token.STRING:
x = p.parseLiteral();
case token.LPAREN:
p.next();
x = p.parseExpression();
if p.tok == token.SHR {
p.next();
x = &group{x, p.parseExpression()};
}
p.expect(token.RPAREN);
case token.LBRACK:
p.next();
x = &option{p.parseExpression()};
p.expect(token.RBRACK);
case token.LBRACE:
p.next();
x = p.parseExpression();
var div expr;
if p.tok == token.QUO {
p.next();
div = p.parseExpression();
}
x = &repetition{x, div};
p.expect(token.RBRACE);
default:
x = p.parseField(); // may be nil
}
return x;
}
func (p *parser) parseSequence() expr {
var list vector.Vector;
list.Init(0);
for x := p.parseOperand(); x != nil; x = p.parseOperand() {
list.Push(x);
}
// no need for a sequence if list.Len() < 2
switch list.Len() {
case 0: return nil;
case 1: return list.At(0).(expr);
}
// convert list into a sequence
seq := make(sequence, list.Len());
for i := 0; i < list.Len(); i++ {
seq[i] = list.At(i).(expr);
}
return seq;
}
func (p *parser) parseExpression() expr {
var list vector.Vector;
list.Init(0);
for {
x := p.parseSequence();
if x != nil {
list.Push(x);
}
if p.tok != token.OR {
break;
}
p.next();
}
// no need for an alternatives if list.Len() < 2
switch list.Len() {
case 0: return nil;
case 1: return list.At(0).(expr);
}
// convert list into a alternatives
alt := make(alternatives, list.Len());
for i := 0; i < list.Len(); i++ {
alt[i] = list.At(i).(expr);
}
return alt;
}
func (p *parser) parseFormat() {
for p.tok != token.EOF {
pos := p.pos;
name, isIdent := p.parseRuleName();
switch p.tok {
case token.STRING:
// package declaration
importPath := p.parseString();
// add package declaration
if !isIdent {
p.Error(pos, "illegal package name: " + name);
} else if _, found := p.packs[name]; !found {
p.packs[name] = importPath;
} else {
p.Error(pos, "package already declared: " + name);
}
case token.ASSIGN:
// format rule
p.next();
x := p.parseExpression();
// add rule
if _, found := p.rules[name]; !found {
p.rules[name] = x;
} else {
p.Error(pos, "format rule already declared: " + name);
}
default:
p.errorExpected(p.pos, "package declaration or format rule");
p.next(); // make progress in any case
}
if p.tok == token.SEMICOLON {
p.next();
} else {
break;
}
}
p.expect(token.EOF);
}
func remap(p *parser, name string) string {
i := strings.Index(name, ".");
if i >= 0 {
packageName := name[0 : i];
typeName := name[i : len(name)];
// lookup package
if importPath, found := p.packs[packageName]; found {
name = importPath + "." + typeName;
} else {
var invalidPos token.Position;
p.Error(invalidPos, "package not declared: " + packageName);
}
}
return name;
}
// Parse parses a set of format productions from source src. Custom
// formatters may be provided via a map of formatter functions. If
// there are no errors, the result is a Format and the error is nil.
// Otherwise the format is nil and a non-empty ErrorList is returned.
//
func Parse(src []byte, fmap FormatterMap) (Format, os.Error) {
// parse source
var p parser;
p.init(src);
p.parseFormat();
// add custom formatters, if any
for name, form := range fmap {
name = remap(&p, name);
if t, found := p.rules[name]; !found {
p.rules[name] = &custom{name, form};
} else {
var invalidPos token.Position;
p.Error(invalidPos, "formatter already declared: " + name);
}
}
// convert errors list, if any
if p.errors.Len() > 0 {
errors := make(ErrorList, p.errors.Len());
for i := 0; i < p.errors.Len(); i++ {
errors[i] = p.errors.At(i).(*Error);
}
return nil, errors;
}
return p.rules, nil;
}

2
usr/gri/pretty/Makefile
View File

@ -32,7 +32,7 @@ clean:
godoc.6: astprinter.6
pretty.6: astprinter.6 format.6
pretty.6: astprinter.6
%.6: %.go
$(G) $(F) $<

58
usr/gri/pretty/ast.txt
View File

@ -13,7 +13,7 @@ token "token";
array =
*;
pointer =
ptr =
*;
string =
@ -47,6 +47,9 @@ token.Token =
^:string;
ast.Comment =
// TODO this doesn't indent properly after //-style comments because
// the '\n'-char is printed as part of the comment - need to
// address this
Text:string [Text:isMultiLineComment "\n"];
ast.Comments =
@ -84,7 +87,7 @@ ast.StringList =
{Strings / "\n"};
ast.FuncLit =
Type " " Body;
Type " " Body ^:clearOptSemi; // no optional ; after a func literal body
ast.CompositeLit =
Type "{" {Elts / ", "} "}";
@ -123,9 +126,9 @@ ast.StructType =
"struct"
[Lbrace:isValidPos " {"]
[ Fields:exists
>> "\t" "\n"
( "\t" >> "\n"
{Fields / ";\n"}
<< "\n"
) "\n"
]
[Rbrace:isValidPos "}"];
@ -142,9 +145,9 @@ ast.InterfaceType =
"interface"
[Lbrace:isValidPos " {"]
[ Methods:exists
>> "\t" "\n"
( "\t" >> "\n"
{Methods / ";\n"}
<< "\n"
) "\n"
]
[Rbrace:isValidPos "}"];
@ -197,14 +200,17 @@ ast.ReturnStmt =
ast.BranchStmt =
Tok [" " Label];
stmtList =
{^ / ^:optSemi "\n"};
blockStmt = // like ast.BlockStmt but w/o indentation
"{"
[List:exists
"\n"
{List / ";\n"}
List:stmtList
"\n"
]
"}";
"}" ^:setOptSemi;
blockStmtPtr =
*:blockStmt;
@ -212,11 +218,11 @@ blockStmtPtr =
ast.BlockStmt =
"{"
[List:exists
>> "\t" "\n"
{List / ";\n"}
<< "\n"
( "\t" >> "\n"
List:stmtList
) "\n"
]
"}";
"}" ^:setOptSemi;
ast.IfStmt =
"if " [Init "; "] [Cond " "] Body [" else " Else];
@ -227,9 +233,9 @@ ast.CaseClause =
)
":"
[Body:exists
>> "\t" "\n"
{Body / ";\n"}
<<
( "\t" >> "\n"
Body:stmtList
)
];
ast.SwitchStmt =
@ -242,9 +248,9 @@ ast.TypeCaseClause =
)
":"
[Body:exists
>> "\t" "\n"
{Body / ";\n"}
<<
( "\t" >> "\n"
Body:stmtList
)
];
ast.TypeSwitchStmt =
@ -257,9 +263,9 @@ ast.CommClause =
)
":"
[Body:exists
>> "\t" "\n"
{Body / ";\n"}
<<
( "\t" >> "\n"
Body:stmtList
)
];
ast.SelectStmt =
@ -303,11 +309,13 @@ ast.BadDecl =
ast.GenDecl =
Doc
Tok " "
( Lparen:isValidPos
>> "\t" "(\n"
( Lparen:isValidPos "("
[Specs:exists
( "\t" >> "\n"
{Specs / ";\n"}
<<
"\n)"
) "\n"
]
")" ^:setOptSemi
| {Specs / ";\n"}
);

967
usr/gri/pretty/format.go
View File

@ -1,967 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
/* The format package implements syntax-directed, type-driven formatting
of arbitrary data structures. Formatting a data structure consists of
two phases: first, a format specification is parsed (once per format)
which results in a "compiled" format. The format can then be used
repeatedly to print arbitrary values to a io.Writer.
A format specification consists of a set of named format rules in EBNF.
The rule names correspond to the type names of the data structure to be
formatted. Each format rule consists of literal values and struct field
names which are combined into sequences, alternatives, grouped, optional,
repeated, or indented sub-expressions. Additionally, format rules may be
specified via Go formatter functions.
When formatting a value, its type name determines the format rule. The
syntax of the rule or the corresponding formatter function determines
if and how the value is formatted. A format rule may refer to a struct
field of the current value. In this case the same mechanism is applied
recursively to that field.
*/
package format
import (
"container/vector";
"flag";
"fmt";
"go/scanner";
"go/token";
"io";
"os";
"reflect";
"runtime";
"strconv";
"strings";
)
// ----------------------------------------------------------------------------
// Format representation
// Custom formatters implement the Formatter function type.
// A formatter is invoked with a writer w, an environment env
// (provided to format.Fprint and simply passed through), the
// value to format, and the rule name under which the formatter
// was installed (the same formatter function may be installed
// under different names).
//
type Formatter func(w io.Writer, env, value interface{}, rule_name string) bool
// A FormatterMap is a set of custom formatters.
// It maps a rule name to a formatter.
//
type FormatterMap map [string] Formatter;
// A production expression is built from the following nodes.
//
type (
expr interface {};
alternatives []expr; // x | y | z
sequence []expr; // x y z
// a literal is represented as string or []byte
field struct {
field_name string; // including "^", "*"
rule_name string; // "" if no rule name specified
};
indentation struct {
indent, body expr; // >> indent body <<
};
option struct {
body expr; // [body]
};
repetition struct {
body, div expr; // {body / div}
};
custom struct {
rule_name string;
form Formatter
};
)
/* The syntax of a format specification is presented in the same EBNF
notation as used in the Go language spec. The syntax of white space,
comments, identifiers, and string literals is the same as in Go.
A format specification consists of a possibly empty set of package
declarations and format rules:
Format = [ Entry { ";" Entry } ] [ ";" ] .
Entry = PackageDecl | FormatRule .
A package declaration binds a package name (such as 'ast') to a
package import path (such as '"go/ast"'). A package name must be
declared at most once.
PackageDecl = PackageName ImportPath .
PackageName = identifier .
ImportPath = string .
A format rule binds a rule name to a format expression. A rule name
may be a type name or one of the special names 'default' (denoting
the default rule) or '/' (denoting the global "divider" rule - see
below). A type name may be the name of a predeclared type ('int',
'float32', etc.), the name of an anonymous composite type ('array',
'pointer', etc.), or the name of a user-defined type qualified by
the corresponding package name (for instance 'ast.MapType'). The
package name must have been declared already. A rule name must be
declared at most once.
FormatRule = RuleName "=" Expression .
RuleName = TypeName | "default" | "/" .
TypeName = [ PackageName "." ] identifier .
A format expression specifies how a value is to be formatted. In its
most general form, a format expression is a set of alternatives separated
by "|". Each alternative and the entire expression may be empty.
Expression = [ Sequence ] { "|" [ Sequence ] } .
Sequence = Operand { Operand } .
Operand = Literal | Field | Indentation | Group | Option | Repetition .
Literal = string .
Field = FieldName [ ":" RuleName ] .
FieldName = identifier | "^" | "*" .
Indent = ">>" Operand Expression "<<" .
Group = "(" Expression ")" .
Option = "[" Expression "]" .
Repetition = "{" Expression [ "/" Expression ] "}" .
TODO complete this comment
*/
type Format map [string] expr;
// ----------------------------------------------------------------------------
// Error handling
// Error describes an individual error. The position Pos, if valid,
// indicates the format source position the error relates to. The
// error is specified with the Msg string.
//
type Error struct {
Pos token.Position;
Msg string;
}
// Error implements the os.Error interface.
func (e *Error) String() string {
pos := "";
if e.Pos.IsValid() {
pos = fmt.Sprintf("%d:%d: ", e.Pos.Line, e.Pos.Column);
}
return pos + e.Msg;
}
// Multiple parser errors are returned as an ErrorList.
type ErrorList []*Error
// ErrorList implements the SortInterface.
func (p ErrorList) Len() int { return len(p); }
func (p ErrorList) Swap(i, j int) { p[i], p[j] = p[j], p[i]; }
func (p ErrorList) Less(i, j int) bool { return p[i].Pos.Offset < p[j].Pos.Offset; }
// ErrorList implements the os.Error interface.
func (p ErrorList) String() string {
switch len(p) {
case 0: return "unspecified error";
case 1: return p[0].String();
}
return fmt.Sprintf("%s (and %d more errors)", p[0].String(), len(p) - 1);
}
// ----------------------------------------------------------------------------
// Parsing
type parser struct {
errors vector.Vector;
scanner scanner.Scanner;
pos token.Position; // token position
tok token.Token; // one token look-ahead
lit []byte; // token literal
packs map [string] string; // PackageName -> ImportPath
rules Format; // RuleName -> Expression
}
// The parser implements scanner.Error.
func (p *parser) Error(pos token.Position, msg string) {
// Don't collect errors that are on the same line as the previous error
// in the hope to reduce the number of spurious errors due to incorrect
// parser synchronization.
if p.errors.Len() == 0 || p.errors.Last().(*Error).Pos.Line != pos.Line {
p.errors.Push(&Error{pos, msg});
}
}
func (p *parser) next() {
p.pos, p.tok, p.lit = p.scanner.Scan();
}
func (p *parser) error_expected(pos token.Position, msg string) {
msg = "expected " + msg;
if pos.Offset == p.pos.Offset {
// the error happened at the current position;
// make the error message more specific
msg += ", found '" + p.tok.String() + "'";
if p.tok.IsLiteral() {
msg += " " + string(p.lit);
}
}
p.Error(pos, msg);
}
func (p *parser) expect(tok token.Token) token.Position {
pos := p.pos;
if p.tok != tok {
p.error_expected(pos, "'" + tok.String() + "'");
}
p.next(); // make progress in any case
return pos;
}
func (p *parser) parseIdentifier() string {
name := string(p.lit);
p.expect(token.IDENT);
return name;
}
func (p *parser) parseTypeName() (string, bool) {
pos := p.pos;
name, is_ident := p.parseIdentifier(), true;
if p.tok == token.PERIOD {
// got a package name, lookup package
if import_path, found := p.packs[name]; found {
name = import_path;
} else {
p.Error(pos, "package not declared: " + name);
}
p.next();
name, is_ident = name + "." + p.parseIdentifier(), false;
}
return name, is_ident;
}
// Parses a rule name and returns it. If the rule name is
// a package-qualified type name, the package name is resolved.
// The 2nd result value is true iff the rule name consists of a
// single identifier only (and thus could be a package name).
//
func (p *parser) parseRuleName() (string, bool) {
name, is_ident := "", false;
switch p.tok {
case token.IDENT:
name, is_ident = p.parseTypeName();
case token.DEFAULT:
name = "default";
p.next();
case token.QUO:
name = "/";
p.next();
default:
p.error_expected(p.pos, "rule name");
p.next(); // make progress in any case
}
return name, is_ident;
}
func asLiteral(x interface{}) expr {
s := x.(string);
if len(s) > 0 && s[0] == '%' {
// literals containing format characters are represented as strings
return s;
}
// all other literals are represented as []byte for faster writing
return io.StringBytes(s);
}
func (p *parser) parseLiteral() expr {
if p.tok != token.STRING {
p.expect(token.STRING);
return "";
}
s, err := strconv.Unquote(string(p.lit));
if err != nil {
panic("scanner error");
}
p.next();
// A string literal may contain newline characters and %-format specifiers.
// To simplify and speed up printing of the literal, split it into segments
// that start with "\n" or "%" (but noy "%%"), possibly followed by a last
// segment that starts with some other character. If there is more than one
// such segment, return a sequence of "simple" literals, otherwise just
// return the string.
// split string
var list vector.Vector;
list.Init(0);
i0 := 0;
for i := 0; i < len(s); i++ {
switch s[i] {
case '\n':
// next segment starts with '\n'
case '%':
if i+1 >= len(s) || s[i+1] == '%' {
i++;
continue; // "%%" is not a format-%
}
// next segment starts with '%'
default:
// all other cases do not split the string
continue;
}
// split off the current segment
if i0 < i {
list.Push(s[i0 : i]);
i0 = i;
}
}
// the final segment may start with any character
// (it is empty iff the string is empty)
list.Push(s[i0 : len(s)]);
// no need for a sequence there is only one segment
if list.Len() == 1 {
return asLiteral(list.At(0));
}
// convert list into a sequence
seq := make(sequence, list.Len());
for i := 0; i < list.Len(); i++ {
seq[i] = asLiteral(list.At(i));
}
return seq;
}
func (p *parser) parseField() expr {
var fname string;
switch p.tok {
case token.XOR:
fname = "^";
p.next();
case token.MUL:
fname = "*";
p.next();
case token.IDENT:
// TODO(gri) could use reflect.ExpandType() to lookup a field
// at parse-time - would provide "compile-time" errors and
// faster printing.
fname = p.parseIdentifier();
default:
return nil;
}
var rule_name string;
if p.tok == token.COLON {
p.next();
var _ bool;
rule_name, _ = p.parseRuleName();
}
return &field{fname, rule_name};
}
func (p *parser) parseExpression() expr
func (p *parser) parseOperand() (x expr) {
switch p.tok {
case token.STRING:
x = p.parseLiteral();
case token.SHR:
p.next();
x = &indentation{p.parseOperand(), p.parseExpression()};
p.expect(token.SHL);
case token.LPAREN:
p.next();
x = p.parseExpression();
p.expect(token.RPAREN);
case token.LBRACK:
p.next();
x = &option{p.parseExpression()};
p.expect(token.RBRACK);
case token.LBRACE:
p.next();
x = p.parseExpression();
var div expr;
if p.tok == token.QUO {
p.next();
div = p.parseExpression();
}
x = &repetition{x, div};
p.expect(token.RBRACE);
default:
x = p.parseField(); // may be nil
}
return x;
}
func (p *parser) parseSequence() expr {
var list vector.Vector;
list.Init(0);
for x := p.parseOperand(); x != nil; x = p.parseOperand() {
list.Push(x);
}
// no need for a sequence if list.Len() < 2
switch list.Len() {
case 0: return nil;
case 1: return list.At(0).(expr);
}
// convert list into a sequence
seq := make(sequence, list.Len());
for i := 0; i < list.Len(); i++ {
seq[i] = list.At(i).(expr);
}
return seq;
}
func (p *parser) parseExpression() expr {
var list vector.Vector;
list.Init(0);
for {
x := p.parseSequence();
if x != nil {
list.Push(x);
}
if p.tok != token.OR {
break;
}
p.next();
}
// no need for an alternatives if list.Len() < 2
switch list.Len() {
case 0: return nil;
case 1: return list.At(0).(expr);
}
// convert list into a alternatives
alt := make(alternatives, list.Len());
for i := 0; i < list.Len(); i++ {
alt[i] = list.At(i).(expr);
}
return alt;
}
func (p *parser) parseFormat() {
for p.tok != token.EOF {
pos := p.pos;
name, is_ident := p.parseRuleName();
switch p.tok {
case token.STRING:
// package declaration
import_path, err := strconv.Unquote(string(p.lit));
if err != nil {
panic("scanner error");
}
p.next();
// add package declaration
if !is_ident {
p.Error(pos, "illegal package name: " + name);
} else if _, found := p.packs[name]; !found {
p.packs[name] = import_path;
} else {
p.Error(pos, "package already declared: " + name);
}
case token.ASSIGN:
// format rule
p.next();
x := p.parseExpression();
// add rule
if _, found := p.rules[name]; !found {
p.rules[name] = x;
} else {
p.Error(pos, "format rule already declared: " + name);
}
default:
p.error_expected(p.pos, "package declaration or format rule");
p.next(); // make progress in any case
}
if p.tok == token.SEMICOLON {
p.next();
} else {
break;
}
}
p.expect(token.EOF);
}
func (p *parser) remap(pos token.Position, name string) string {
i := strings.Index(name, ".");
if i >= 0 {
package_name := name[0 : i];
type_name := name[i : len(name)];
// lookup package
if import_path, found := p.packs[package_name]; found {
name = import_path + "." + type_name;
} else {
p.Error(pos, "package not declared: " + package_name);
}
}
return name;
}
// Parse parses a set of format productions from source src. If there are no
// errors, the result is a Format and the error is nil. Otherwise the format
// is nil and a non-empty ErrorList is returned.
//
func Parse(src []byte, fmap FormatterMap) (Format, os.Error) {
// parse source
var p parser;
p.errors.Init(0);
p.scanner.Init(src, &p, false);
p.next();
p.packs = make(map [string] string);
p.rules = make(Format);
p.parseFormat();
// add custom formatters, if any
var invalidPos token.Position;
for name, form := range fmap {
name = p.remap(invalidPos, name);
if t, found := p.rules[name]; !found {
p.rules[name] = &custom{name, form};
} else {
var invalidPos token.Position;
p.Error(invalidPos, "formatter already declared: " + name);
}
}
// convert errors list, if any
if p.errors.Len() > 0 {
errors := make(ErrorList, p.errors.Len());
for i := 0; i < p.errors.Len(); i++ {
errors[i] = p.errors.At(i).(*Error);
}
return nil, errors;
}
return p.rules, nil;
}
// ----------------------------------------------------------------------------
// Formatting
// The current formatting state.
type state struct {
f Format; // the format used
env interface{}; // the user-supplied environment, simply passed through
def expr; // the default rule, if any
div expr; // the global divider rule, if any
writediv bool; // true if the divider needs to be written
errors chan os.Error; // not chan *Error: errors <- nil would be wrong!
indent io.ByteBuffer; // the current indentation
}
func (ps *state) init(f Format, env interface{}, errors chan os.Error) {
ps.f = f;
ps.env = env;
// if we have a default ("default") rule, cache it for fast access
if def, has_def := f["default"]; has_def {
ps.def = def;
}
// if we have a divider ("/") rule, cache it for fast access
if div, has_div := f["/"]; has_div {
ps.div = div;
}
ps.errors = errors;
}
func (ps *state) error(msg string) {
ps.errors <- os.NewError(msg);
runtime.Goexit();
}
// Get a field value given a field name. Returns the field value and
// the "embedding level" at which it was found. The embedding level
// is 0 for top-level fields in a struct.
//
func getField(val reflect.Value, fieldname string) (reflect.Value, int) {
// do we have a struct in the first place?
if val.Kind() != reflect.StructKind {
return nil, 0;
}
sval, styp := val.(reflect.StructValue), val.Type().(reflect.StructType);
// look for field at the top level
for i := 0; i < styp.Len(); i++ {
name, typ, tag, offset := styp.Field(i);
if name == fieldname || name == "" && strings.HasSuffix(typ.Name(), "." + fieldname) /* anonymous field */ {
return sval.Field(i), 0;
}
}
// look for field in anonymous fields
var field reflect.Value;
level := 1000; // infinity (no struct has that many levels)
for i := 0; i < styp.Len(); i++ {
name, typ, tag, offset := styp.Field(i);
if name == "" {
f, l := getField(sval.Field(i), fieldname);
// keep the most shallow field
if f != nil && l < level {
field, level = f, l;
}
}
}
return field, level + 1;
}
var default_names = map[int]string {
reflect.ArrayKind: "array",
reflect.BoolKind: "bool",
reflect.ChanKind: "chan",
reflect.DotDotDotKind: "ellipsis",
reflect.FloatKind: "float",
reflect.Float32Kind: "float32",
reflect.Float64Kind: "float64",
reflect.FuncKind: "func",
reflect.IntKind: "int",
reflect.Int16Kind: "int16",
reflect.Int32Kind: "int32",
reflect.Int64Kind: "int64",
reflect.Int8Kind: "int8",
reflect.InterfaceKind: "interface",
reflect.MapKind: "map",
reflect.PtrKind: "pointer",
reflect.StringKind: "string",
reflect.StructKind: "struct",
reflect.UintKind: "uint",
reflect.Uint16Kind: "uint16",
reflect.Uint32Kind: "uint32",
reflect.Uint64Kind: "uint64",
reflect.Uint8Kind: "uint8",
reflect.UintptrKind: "uintptr",
}
func typename(value reflect.Value) string {
name := value.Type().Name();
if name == "" {
if default_name, found := default_names[value.Kind()]; found {
name = default_name;
}
}
return name;
}
func (ps *state) getFormat(name string) expr {
if fexpr, found := ps.f[name]; found {
return fexpr;
}
if ps.def != nil {
return ps.def;
}
ps.error(fmt.Sprintf("no production for type: '%s'\n", name));
return nil;
}
func (ps *state) printf(w io.Writer, fexpr expr, value reflect.Value, index int) bool
func (ps *state) printDiv(w io.Writer, value reflect.Value) {
if ps.div != nil && ps.writediv {
div := ps.div;
ps.div = nil;
ps.printf(w, div, value, 0);
ps.div = div;
}
ps.writediv = true;
}
func (ps *state) writeIndented(w io.Writer, s []byte) {
// write indent after each '\n'
i0 := 0;
for i := 0; i < len(s); i++ {
if s[i] == '\n' {
w.Write(s[i0 : i+1]);
w.Write(ps.indent.Data());
i0 = i+1;
}
}
w.Write(s[i0 : len(s)]);
}
// TODO complete this comment
// Returns true if a non-empty field value was found.
func (ps *state) printf(w io.Writer, fexpr expr, value reflect.Value, index int) bool {
if fexpr == nil {
return true;
}
switch t := fexpr.(type) {
case alternatives:
// - write first non-empty alternative
// - result is not empty iff there is an non-empty alternative
for _, x := range t {
var buf io.ByteBuffer;
if ps.printf(&buf, x, value, 0) {
w.Write(buf.Data());
return true;
}
}
return false;
case sequence:
// - write every element of the sequence
// - result is not empty iff no element was empty
b := true;
for _, x := range t {
b = ps.printf(w, x, value, index) && b;
}
return b;
case []byte:
// write literal, may start with "\n"
ps.printDiv(w, value);
if len(t) > 0 && t[0] == '\n' && ps.indent.Len() > 0 {
// newline must be followed by indentation
w.Write([]byte{'\n'});
w.Write(ps.indent.Data());
t = t[1 : len(t)];
}
w.Write(t);
return true;
case string:
// write format literal with value, starts with "%" (but not "%%")
ps.printDiv(w, value);
fmt.Fprintf(w, t, value.Interface());
return true;
case *field:
// - write the contents of the field
// - format is either the field format or the type-specific format
// - result is not empty iff the field is not empty
switch t.field_name {
case "^":
// identity - value doesn't change
case "*":
// indirect
switch v := value.(type) {
case reflect.ArrayValue:
if v.Len() <= index {
return false;
}
value = v.Elem(index);
case reflect.MapValue:
ps.error("reflection support for maps incomplete\n");
case reflect.PtrValue:
if v.Get() == nil {
return false;
}
value = v.Sub();
case reflect.InterfaceValue:
if v.Get() == nil {
return false;
}
value = v.Value();
default:
ps.error(fmt.Sprintf("error: * does not apply to `%s`\n", value.Type().Name()));
}
default:
// field
field, _ := getField(value, t.field_name);
if field == nil {
ps.error(fmt.Sprintf("error: no field `%s` in `%s`\n", t.field_name, value.Type().Name()));
}
value = field;
}
// field-specific rule name
rule_name := t.rule_name;
if rule_name == "" {
rule_name = typename(value)
}
fexpr = ps.getFormat(rule_name);
return ps.printf(w, fexpr, value, index);
case *indentation:
// - write the body within the given indentation
// - the result is not empty iff the body is not empty
saved_len := ps.indent.Len();
ps.printf(&ps.indent, t.indent, value, index); // add additional indentation
b := ps.printf(w, t.body, value, index);
ps.indent.Truncate(saved_len); // reset indentation
return b;
case *option:
// - write body if it is not empty
// - the result is always not empty
var buf io.ByteBuffer;
if ps.printf(&buf, t.body, value, 0) {
w.Write(buf.Data());
}
return true;
case *repetition:
// - write body until as long as it is not empty
// - the result is always not empty
var buf io.ByteBuffer;
for i := 0; ps.printf(&buf, t.body, value, i); i++ {
if i > 0 {
ps.printf(w, t.div, value, i);
}
w.Write(buf.Data());
buf.Reset();
}
return true;
case *custom:
// - invoke custom formatter
var buf io.ByteBuffer;
if t.form(&buf, ps.env, value.Interface(), t.rule_name) {
ps.writeIndented(w, buf.Data());
return true;
}
return false;
}
panic("unreachable");
return false;
}
// Sandbox to wrap a writer.
// Counts total number of bytes written and handles write errors.
//
type sandbox struct {
writer io.Writer;
written int;
errors chan os.Error;
}
// Write data to the sandboxed writer. If an error occurs, Write
// doesn't return. Instead it reports the error to the errors
// channel and exits the current goroutine.
//
func (s *sandbox) Write(data []byte) (int, os.Error) {
n, err := s.writer.Write(data);
s.written += n;
if err != nil {
s.errors <- err;
runtime.Goexit();
}
return n, nil;
}
// Fprint formats each argument according to the format f
// and writes to w. The result is the total number of bytes
// written and an os.Error, if any.
//
func (f Format) Fprint(w io.Writer, env interface{}, args ...) (int, os.Error) {
errors := make(chan os.Error);
sw := sandbox{w, 0, errors};
var ps state;
ps.init(f, env, errors);
go func() {
value := reflect.NewValue(args).(reflect.StructValue);
for i := 0; i < value.Len(); i++ {
fld := value.Field(i);
ps.printf(&sw, ps.getFormat(typename(fld)), fld, 0);
}
errors <- nil; // no errors
}();
return sw.written, <-errors;
}
// Print formats each argument according to the format f
// and writes to standard output. The result is the total
// number of bytes written and an os.Error, if any.
//
func (f Format) Print(args ...) (int, os.Error) {
return f.Fprint(os.Stdout, nil, args);
}
// Sprint formats each argument according to the format f
// and returns the resulting string. If an error occurs
// during formatting, the result contains the respective
// error message at the end.
//
func (f Format) Sprint(args ...) string {
var buf io.ByteBuffer;
n, err := f.Fprint(&buf, nil, args);
if err != nil {
fmt.Fprintf(&buf, "--- Sprint(%v) failed: %v", args, err);
}
return string(buf.Data());
}

153
usr/gri/pretty/format_test.go
View File

@ -1,153 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package format
import (
"format";
"io";
"testing";
)
func check(t *testing.T, form, expected string, args ...) {
f, err := format.Parse(io.StringBytes(form), nil);
if err != nil {
panic(form + ": " + err.String());
}
result := f.Sprint(args);
if result != expected {
t.Errorf(
"format : %s\nresult : `%s`\nexpected: `%s`\n\n",
form, result, expected
)
}
}
// ----------------------------------------------------------------------------
// Syntax
func TestA(t *testing.T) {
// TODO fill this in
}
// ----------------------------------------------------------------------------
// - formatting of basic types
func Test0(t *testing.T) {
check(t, `bool = "%v"`, "false", false);
check(t, `int = "%b %d %o 0x%x"`, "101010 42 52 0x2a", 42);
}
// ----------------------------------------------------------------------------
// - formatting of a struct
type T1 struct {
a int;
}
const F1 =
`format "format";`
`int = "%d";`
`format.T1 = "<" a ">";`
func Test1(t *testing.T) {
check(t, F1, "<42>", T1{42});
}
// ----------------------------------------------------------------------------
// - formatting of a struct with an optional field (pointer)
type T2 struct {
s string;
p *T1;
}
const F2a =
F1 +
`string = "%s";`
`pointer = *;`
`format.T2 = s ["-" p "-"];`
const F2b =
F1 +
`string = "%s";`
`pointer = *;`
`format.T2 = s ("-" p "-" | "empty");`;
func Test2(t *testing.T) {
check(t, F2a, "foo", T2{"foo", nil});
check(t, F2a, "bar-<17>-", T2{"bar", &T1{17}});
check(t, F2b, "fooempty", T2{"foo", nil});
}
// ----------------------------------------------------------------------------
// - formatting of a struct with a repetitive field (slice)
type T3 struct {
s string;
a []int;
}
const F3a =
`format "format";`
`default = "%v";`
`array = *;`
`format.T3 = s {" " a a / ","};`
const F3b =
`format "format";`
`int = "%d";`
`string = "%s";`
`array = *;`
`nil = ;`
`empty = *:nil;`
`format.T3 = s [a:empty ": " {a / "-"}]`
func Test3(t *testing.T) {
check(t, F3a, "foo", T3{"foo", nil});
check(t, F3a, "foo 00, 11, 22", T3{"foo", []int{0, 1, 2}});
check(t, F3b, "bar", T3{"bar", nil});
check(t, F3b, "bal: 2-3-5", T3{"bal", []int{2, 3, 5}});
}
// ----------------------------------------------------------------------------
// - formatting of a struct with alternative field
type T4 struct {
x *int;
a []int;
}
const F4a =
`format "format";`
`int = "%d";`
`pointer = *;`
`array = *;`
`nil = ;`
`empty = *:nil;`
`format.T4 = "<" (x:empty x | "-") ">" `
const F4b =
`format "format";`
`int = "%d";`
`pointer = *;`
`array = *;`
`nil = ;`
`empty = *:nil;`
`format.T4 = "<" (a:empty {a / ", "} | "-") ">" `
func Test4(t *testing.T) {
x := 7;
check(t, F4a, "<->", T4{nil, nil});
check(t, F4a, "<7>", T4{&x, nil});
check(t, F4b, "<->", T4{nil, nil});
check(t, F4b, "<2, 3, 7>", T4{nil, []int{2, 3, 7}});
}

52
usr/gri/pretty/pretty.go
View File

@ -70,23 +70,55 @@ func makeTabwriter(writer io.Writer) *tabwriter.Writer {
}
func isValidPos(w io.Writer, env, value interface{}, name string) bool {
func isValidPos(state *format.State, value interface{}, rule_name string) bool {
pos := value.(token.Position);
return pos.IsValid();
}
func isSend(w io.Writer, env, value interface{}, name string) bool {
func isSend(state *format.State, value interface{}, rule_name string) bool {
return value.(ast.ChanDir) & ast.SEND != 0;
}
func isRecv(w io.Writer, env, value interface{}, name string) bool {
func isRecv(state *format.State, value interface{}, rule_name string) bool {
return value.(ast.ChanDir) & ast.RECV != 0;
}
func isMultiLineComment(w io.Writer, env, value interface{}, name string) bool {
return value.([]byte)[1] == '*'
func isMultiLineComment(state *format.State, value interface{}, rule_name string) bool {
return value.([]byte)[1] == '*';
}
type environment struct {
optSemi *bool;
}
func (e environment) Copy() format.Environment {
optSemi := *e.optSemi;
return environment{&optSemi};
}
func clearOptSemi(state *format.State, value interface{}, rule_name string) bool {
*state.Env().(environment).optSemi = false;
return true;
}
func setOptSemi(state *format.State, value interface{}, rule_name string) bool {
*state.Env().(environment).optSemi = true;
return true;
}
func optSemi(state *format.State, value interface{}, rule_name string) bool {
if !*state.Env().(environment).optSemi {
state.Write([]byte{';'});
}
return true;
}
@ -95,6 +127,10 @@ var fmap = format.FormatterMap{
"isSend": isSend,
"isRecv": isRecv,
"isMultiLineComment": isMultiLineComment,
"/": clearOptSemi,
"clearOptSemi": clearOptSemi,
"setOptSemi": setOptSemi,
"optSemi": optSemi,
}
@ -153,10 +189,10 @@ func main() {
if !*silent {
tw := makeTabwriter(os.Stdout);
if *formatter {
var optSemi bool; // formatting environment
_, err := ast_format.Fprint(tw, &optSemi, prog);
env := environment{new(bool)};
_, err := ast_format.Fprint(tw, env, prog);
if err != nil {
fmt.Fprintf(os.Stderr, "format error$$: %s", err);
fmt.Fprintf(os.Stderr, "format error: %v\n", err);
exitcode = 1;
continue; // proceed with next file
}