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exp/template: character constants.

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Easier to implement than to justify leaving them out.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4662089
This commit is contained in:
Rob Pike 2011-07-11 11:46:22 +10:00
parent e7030e7fef
commit bf9531f80b
5 changed files with 98 additions and 14 deletions
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7
src/pkg/exp/template/doc.go
View File

@ -78,10 +78,9 @@ Arguments
An argument is a simple value, denoted by one of the following:
- A boolean, string, integer, floating-point, imaginary or complex
constant in Go syntax. These behave like Go's untyped constants,
although raw strings may not span newlines. (Character constants are
not supported; this may change.)
- A boolean, string, character, integer, floating-point, imaginary
or complex constant in Go syntax. These behave like Go's untyped
constants, although raw strings may not span newlines.
- The character '.' (period):
.
The result is the value of dot.

25
src/pkg/exp/template/lex.go
View File

@ -37,6 +37,7 @@ type itemType int
const (
itemError itemType = iota // error occurred; value is text of error
itemBool // boolean constant
itemChar // character constant
itemComplex // complex constant (1+2i); imaginary is just a number
itemColonEquals // colon-equals (':=') introducing a declaration
itemEOF
@ -66,6 +67,7 @@ const (
var itemName = map[itemType]string{
itemError: "error",
itemBool: "bool",
itemChar: "char",
itemComplex: "complex",
itemColonEquals: ":=",
itemEOF: "EOF",
@ -296,6 +298,8 @@ func lexInsideAction(l *lexer) stateFn {
return lexRawQuote
case r == '$':
return lexIdentifier
case r == '\'':
return lexChar
case r == '.':
// special look-ahead for ".field" so we don't break l.backup().
if l.pos < len(l.input) {
@ -348,6 +352,27 @@ Loop:
return lexInsideAction
}
// lexChar scans a character constant. The initial quote is already
// scanned. Syntax checking is done by the parse.
func lexChar(l *lexer) stateFn {
Loop:
for {
switch l.next() {
case '\\':
if r := l.next(); r != eof && r != '\n' {
break
}
fallthrough
case eof, '\n':
return l.errorf("unterminated character constant")
case '\'':
break Loop
}
}
l.emit(itemChar)
return lexInsideAction
}
// lexNumber scans a number: decimal, octal, hex, float, or imaginary. This
// isn't a perfect number scanner - for instance it accepts "." and "0x0.2"
// and "089" - but when it's wrong the input is invalid and the parser (via

16
src/pkg/exp/template/lex_test.go
View File

@ -53,6 +53,18 @@ var lexTests = []lexTest{
tRight,
tEOF,
}},
{"characters", `{{'a' '\n' '\'' '\\' '\u00FF' '\xFF' '本'}}`, []item{
tLeft,
{itemChar, `'a'`},
{itemChar, `'\n'`},
{itemChar, `'\''`},
{itemChar, `'\\'`},
{itemChar, `'\u00FF'`},
{itemChar, `'\xFF'`},
{itemChar, `'本'`},
tRight,
tEOF,
}},
{"bools", "{{true false}}", []item{
tLeft,
{itemBool, "true"},
@ -137,6 +149,10 @@ var lexTests = []lexTest{
tLeft,
{itemError, "unterminated raw quoted string"},
}},
{"unclosed char constant", "{{'\n}}", []item{
tLeft,
{itemError, "unterminated character constant"},
}},
{"bad number", "{{3k}}", []item{
tLeft,
{itemError, `bad number syntax: "3k"`},

29
src/pkg/exp/template/parse.go
View File

@ -289,9 +289,28 @@ type numberNode struct {
text string
}
func newNumber(text string, isComplex bool) (*numberNode, os.Error) {
func newNumber(text string, typ itemType) (*numberNode, os.Error) {
n := &numberNode{nodeType: nodeNumber, text: text}
if isComplex {
switch typ {
case itemChar:
if len(text) < 3 {
return nil, fmt.Errorf("illegal character constant: %s", text)
}
rune, _, tail, err := strconv.UnquoteChar(text[1:len(text)-1], text[0])
if err != nil {
return nil, err
}
if len(tail) > 0 {
return nil, fmt.Errorf("extra bytes in character constant: %s", text)
}
n.int64 = int64(rune)
n.isInt = true
n.uint64 = uint64(rune)
n.isUint = true
n.float64 = float64(rune) // odd but those are the rules.
n.isFloat = true
return n, nil
case itemComplex:
// fmt.Sscan can parse the pair, so let it do the work.
if _, err := fmt.Sscan(text, &n.complex128); err != nil {
return nil, err
@ -713,7 +732,7 @@ func (t *Template) pipeline(context string) (pipe *pipeNode) {
t.errorf("missing value for %s", context)
}
return
case itemBool, itemComplex, itemDot, itemField, itemIdentifier, itemVariable, itemNumber, itemRawString, itemString:
case itemBool, itemChar, itemComplex, itemDot, itemField, itemIdentifier, itemVariable, itemNumber, itemRawString, itemString:
t.backup()
pipe.append(t.command())
default:
@ -853,8 +872,8 @@ Loop:
cmd.append(newField(token.val))
case itemBool:
cmd.append(newBool(token.val == "true"))
case itemComplex, itemNumber:
number, err := newNumber(token.val, token.typ == itemComplex)
case itemChar, itemComplex, itemNumber:
number, err := newNumber(token.val, token.typ)
if err != nil {
t.error(err)
}

33
src/pkg/exp/template/parse_test.go
View File

@ -29,6 +29,8 @@ var numberTests = []numberTest{
{"0", true, true, true, false, 0, 0, 0, 0},
{"-0", true, true, true, false, 0, 0, 0, 0}, // check that -0 is a uint.
{"73", true, true, true, false, 73, 73, 73, 0},
{"073", true, true, true, false, 073, 073, 073, 0},
{"0x73", true, true, true, false, 0x73, 0x73, 0x73, 0},
{"-73", true, false, true, false, -73, 0, -73, 0},
{"+73", true, false, true, false, 73, 0, 73, 0},
{"100", true, true, true, false, 100, 100, 100, 0},
@ -39,6 +41,7 @@ var numberTests = []numberTest{
{"-1e19", false, false, true, false, 0, 0, -1e19, 0},
{"4i", false, false, false, true, 0, 0, 0, 4i},
{"-1.2+4.2i", false, false, false, true, 0, 0, 0, -1.2 + 4.2i},
{"073i", false, false, false, true, 0, 0, 0, 73i}, // not octal!
// complex with 0 imaginary are float (and maybe integer)
{"0i", true, true, true, true, 0, 0, 0, 0},
{"-1.2+0i", false, false, true, true, 0, 0, -1.2, -1.2},
@ -48,12 +51,23 @@ var numberTests = []numberTest{
{"0123", true, true, true, false, 0123, 0123, 0123, 0},
{"-0x0", true, true, true, false, 0, 0, 0, 0},
{"0xdeadbeef", true, true, true, false, 0xdeadbeef, 0xdeadbeef, 0xdeadbeef, 0},
// character constants
{`'a'`, true, true, true, false, 'a', 'a', 'a', 0},
{`'\n'`, true, true, true, false, '\n', '\n', '\n', 0},
{`'\\'`, true, true, true, false, '\\', '\\', '\\', 0},
{`'\''`, true, true, true, false, '\'', '\'', '\'', 0},
{`'\xFF'`, true, true, true, false, 0xFF, 0xFF, 0xFF, 0},
{`'パ'`, true, true, true, false, 0x30d1, 0x30d1, 0x30d1, 0},
{`'\u30d1'`, true, true, true, false, 0x30d1, 0x30d1, 0x30d1, 0},
{`'\U000030d1'`, true, true, true, false, 0x30d1, 0x30d1, 0x30d1, 0},
// some broken syntax
{text: "+-2"},
{text: "0x123."},
{text: "1e."},
{text: "0xi."},
{text: "1+2."},
{text: "'x"},
{text: "'xx'"},
}
func TestNumberParse(t *testing.T) {
@ -61,11 +75,19 @@ func TestNumberParse(t *testing.T) {
// If fmt.Sscan thinks it's complex, it's complex. We can't trust the output
// because imaginary comes out as a number.
var c complex128
typ := itemNumber
if test.text[0] == '\'' {
typ = itemChar
} else {
_, err := fmt.Sscan(test.text, &c)
n, err := newNumber(test.text, err == nil)
if err == nil {
typ = itemComplex
}
}
n, err := newNumber(test.text, typ)
ok := test.isInt || test.isUint || test.isFloat || test.isComplex
if ok && err != nil {
t.Errorf("unexpected error for %q", test.text)
t.Errorf("unexpected error for %q: %s", test.text, err)
continue
}
if !ok && err == nil {
@ -73,6 +95,9 @@ func TestNumberParse(t *testing.T) {
continue
}
if !ok {
if *debug {
fmt.Printf("%s\n\t%s\n", test.text, err)
}
continue
}
if n.isComplex != test.isComplex {
@ -174,8 +199,8 @@ var parseTests = []parseTest{
`[({{range [(command: [F=[X]]) (command: [F=[M]])]}} [(text: "true")] {{else}} [(text: "false")])]`},
{"range []int", "{{range .SI}}{{.}}{{end}}", noError,
`[({{range [(command: [F=[SI]])]}} [(action: [(command: [{{<.>}}])])])]`},
{"constants", "{{range .SI 1 -3.2i true false }}{{end}}", noError,
`[({{range [(command: [F=[SI] N=1 N=-3.2i B=true B=false])]}} [])]`},
{"constants", "{{range .SI 1 -3.2i true false 'a'}}{{end}}", noError,
`[({{range [(command: [F=[SI] N=1 N=-3.2i B=true B=false N='a'])]}} [])]`},
{"template", "{{template `x`}}", noError,
"[{{template S=`x`}}]"},
{"template", "{{template `x` .Y}}", noError,