mirror of
https://github.com/golang/go
synced 2024-10-04 20:21:22 -06:00
e11d94fcd7
Fixes issue #1896. R=golang-dev, dsymonds CC=golang-dev https://golang.org/cl/4539093
1138 lines
30 KiB
Go
1138 lines
30 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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/*
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Package template implements data-driven templates for generating textual
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output such as HTML.
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Templates are executed by applying them to a data structure.
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Annotations in the template refer to elements of the data
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structure (typically a field of a struct or a key in a map)
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to control execution and derive values to be displayed.
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The template walks the structure as it executes and the
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"cursor" @ represents the value at the current location
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in the structure.
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Data items may be values or pointers; the interface hides the
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indirection.
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In the following, 'field' is one of several things, according to the data.
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- The name of a field of a struct (result = data.field),
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- The value stored in a map under that key (result = data[field]), or
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- The result of invoking a niladic single-valued method with that name
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(result = data.field())
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Major constructs ({} are the default delimiters for template actions;
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[] are the notation in this comment for optional elements):
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{# comment }
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A one-line comment.
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{.section field} XXX [ {.or} YYY ] {.end}
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Set @ to the value of the field. It may be an explicit @
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to stay at the same point in the data. If the field is nil
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or empty, execute YYY; otherwise execute XXX.
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{.repeated section field} XXX [ {.alternates with} ZZZ ] [ {.or} YYY ] {.end}
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Like .section, but field must be an array or slice. XXX
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is executed for each element. If the array is nil or empty,
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YYY is executed instead. If the {.alternates with} marker
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is present, ZZZ is executed between iterations of XXX.
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{field}
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{field1 field2 ...}
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{field|formatter}
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{field1 field2...|formatter}
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{field|formatter1|formatter2}
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Insert the value of the fields into the output. Each field is
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first looked for in the cursor, as in .section and .repeated.
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If it is not found, the search continues in outer sections
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until the top level is reached.
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If the field value is a pointer, leading asterisks indicate
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that the value to be inserted should be evaluated through the
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pointer. For example, if x.p is of type *int, {x.p} will
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insert the value of the pointer but {*x.p} will insert the
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value of the underlying integer. If the value is nil or not a
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pointer, asterisks have no effect.
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If a formatter is specified, it must be named in the formatter
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map passed to the template set up routines or in the default
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set ("html","str","") and is used to process the data for
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output. The formatter function has signature
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func(wr io.Writer, formatter string, data ...interface{})
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where wr is the destination for output, data holds the field
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values at the instantiation, and formatter is its name at
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the invocation site. The default formatter just concatenates
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the string representations of the fields.
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Multiple formatters separated by the pipeline character | are
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executed sequentially, with each formatter receiving the bytes
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emitted by the one to its left.
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As well as field names, one may use literals with Go syntax.
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Integer, floating-point, and string literals are supported.
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Raw strings may not span newlines.
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The delimiter strings get their default value, "{" and "}", from
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JSON-template. They may be set to any non-empty, space-free
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string using the SetDelims method. Their value can be printed
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in the output using {.meta-left} and {.meta-right}.
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*/
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package template
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import (
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"bytes"
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"container/vector"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"reflect"
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"strconv"
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"strings"
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"unicode"
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"utf8"
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)
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// Errors returned during parsing and execution. Users may extract the information and reformat
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// if they desire.
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type Error struct {
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Line int
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Msg string
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}
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func (e *Error) String() string { return fmt.Sprintf("line %d: %s", e.Line, e.Msg) }
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// Most of the literals are aces.
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var lbrace = []byte{'{'}
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var rbrace = []byte{'}'}
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var space = []byte{' '}
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var tab = []byte{'\t'}
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// The various types of "tokens", which are plain text or (usually) brace-delimited descriptors
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const (
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tokAlternates = iota
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tokComment
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tokEnd
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tokLiteral
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tokOr
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tokRepeated
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tokSection
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tokText
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tokVariable
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)
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// FormatterMap is the type describing the mapping from formatter
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// names to the functions that implement them.
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type FormatterMap map[string]func(io.Writer, string, ...interface{})
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// Built-in formatters.
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var builtins = FormatterMap{
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"html": HTMLFormatter,
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"str": StringFormatter,
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"": StringFormatter,
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}
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// The parsed state of a template is a vector of xxxElement structs.
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// Sections have line numbers so errors can be reported better during execution.
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// Plain text.
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type textElement struct {
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text []byte
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}
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// A literal such as .meta-left or .meta-right
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type literalElement struct {
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text []byte
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}
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// A variable invocation to be evaluated
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type variableElement struct {
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linenum int
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args []interface{} // The fields and literals in the invocation.
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fmts []string // Names of formatters to apply. len(fmts) > 0
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}
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// A variableElement arg to be evaluated as a field name
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type fieldName string
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// A .section block, possibly with a .or
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type sectionElement struct {
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linenum int // of .section itself
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field string // cursor field for this block
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start int // first element
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or int // first element of .or block
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end int // one beyond last element
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}
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// A .repeated block, possibly with a .or and a .alternates
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type repeatedElement struct {
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sectionElement // It has the same structure...
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altstart int // ... except for alternates
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altend int
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}
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// Template is the type that represents a template definition.
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// It is unchanged after parsing.
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type Template struct {
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fmap FormatterMap // formatters for variables
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// Used during parsing:
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ldelim, rdelim []byte // delimiters; default {}
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buf []byte // input text to process
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p int // position in buf
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linenum int // position in input
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// Parsed results:
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elems *vector.Vector
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}
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// Internal state for executing a Template. As we evaluate the struct,
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// the data item descends into the fields associated with sections, etc.
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// Parent is used to walk upwards to find variables higher in the tree.
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type state struct {
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parent *state // parent in hierarchy
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data reflect.Value // the driver data for this section etc.
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wr io.Writer // where to send output
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buf [2]bytes.Buffer // alternating buffers used when chaining formatters
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}
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func (parent *state) clone(data reflect.Value) *state {
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return &state{parent: parent, data: data, wr: parent.wr}
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}
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// New creates a new template with the specified formatter map (which
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// may be nil) to define auxiliary functions for formatting variables.
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func New(fmap FormatterMap) *Template {
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t := new(Template)
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t.fmap = fmap
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t.ldelim = lbrace
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t.rdelim = rbrace
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t.elems = new(vector.Vector)
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return t
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}
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// Report error and stop executing. The line number must be provided explicitly.
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func (t *Template) execError(st *state, line int, err string, args ...interface{}) {
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panic(&Error{line, fmt.Sprintf(err, args...)})
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}
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// Report error, panic to terminate parsing.
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// The line number comes from the template state.
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func (t *Template) parseError(err string, args ...interface{}) {
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panic(&Error{t.linenum, fmt.Sprintf(err, args...)})
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}
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// Is this an exported - upper case - name?
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func isExported(name string) bool {
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rune, _ := utf8.DecodeRuneInString(name)
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return unicode.IsUpper(rune)
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}
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// -- Lexical analysis
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// Is c a white space character?
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func white(c uint8) bool { return c == ' ' || c == '\t' || c == '\r' || c == '\n' }
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// Safely, does s[n:n+len(t)] == t?
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func equal(s []byte, n int, t []byte) bool {
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b := s[n:]
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if len(t) > len(b) { // not enough space left for a match.
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return false
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}
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for i, c := range t {
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if c != b[i] {
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return false
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}
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}
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return true
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}
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// isQuote returns true if c is a string- or character-delimiting quote character.
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func isQuote(c byte) bool {
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return c == '"' || c == '`' || c == '\''
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}
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// endQuote returns the end quote index for the quoted string that
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// starts at n, or -1 if no matching end quote is found before the end
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// of the line.
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func endQuote(s []byte, n int) int {
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quote := s[n]
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for n++; n < len(s); n++ {
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switch s[n] {
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case '\\':
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if quote == '"' || quote == '\'' {
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n++
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}
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case '\n':
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return -1
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case quote:
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return n
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}
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}
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return -1
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}
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// nextItem returns the next item from the input buffer. If the returned
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// item is empty, we are at EOF. The item will be either a
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// delimited string or a non-empty string between delimited
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// strings. Tokens stop at (but include, if plain text) a newline.
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// Action tokens on a line by themselves drop any space on
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// either side, up to and including the newline.
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func (t *Template) nextItem() []byte {
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startOfLine := t.p == 0 || t.buf[t.p-1] == '\n'
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start := t.p
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var i int
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newline := func() {
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t.linenum++
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i++
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}
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// Leading white space up to but not including newline
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for i = start; i < len(t.buf); i++ {
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if t.buf[i] == '\n' || !white(t.buf[i]) {
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break
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}
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}
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leadingSpace := i > start
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// What's left is nothing, newline, delimited string, or plain text
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switch {
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case i == len(t.buf):
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// EOF; nothing to do
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case t.buf[i] == '\n':
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newline()
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case equal(t.buf, i, t.ldelim):
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left := i // Start of left delimiter.
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right := -1 // Will be (immediately after) right delimiter.
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haveText := false // Delimiters contain text.
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i += len(t.ldelim)
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// Find the end of the action.
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for ; i < len(t.buf); i++ {
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if t.buf[i] == '\n' {
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break
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}
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if isQuote(t.buf[i]) {
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i = endQuote(t.buf, i)
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if i == -1 {
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t.parseError("unmatched quote")
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return nil
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}
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continue
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}
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if equal(t.buf, i, t.rdelim) {
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i += len(t.rdelim)
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right = i
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break
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}
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haveText = true
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}
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if right < 0 {
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t.parseError("unmatched opening delimiter")
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return nil
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}
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// Is this a special action (starts with '.' or '#') and the only thing on the line?
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if startOfLine && haveText {
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firstChar := t.buf[left+len(t.ldelim)]
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if firstChar == '.' || firstChar == '#' {
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// It's special and the first thing on the line. Is it the last?
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for j := right; j < len(t.buf) && white(t.buf[j]); j++ {
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if t.buf[j] == '\n' {
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// Yes it is. Drop the surrounding space and return the {.foo}
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t.linenum++
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t.p = j + 1
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return t.buf[left:right]
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}
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}
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}
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}
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// No it's not. If there's leading space, return that.
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if leadingSpace {
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// not trimming space: return leading white space if there is some.
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t.p = left
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return t.buf[start:left]
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}
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// Return the word, leave the trailing space.
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start = left
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break
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default:
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for ; i < len(t.buf); i++ {
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if t.buf[i] == '\n' {
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newline()
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break
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}
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if equal(t.buf, i, t.ldelim) {
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break
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}
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}
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}
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item := t.buf[start:i]
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t.p = i
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return item
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}
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// Turn a byte array into a white-space-split array of strings,
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// taking into account quoted strings.
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func words(buf []byte) []string {
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s := make([]string, 0, 5)
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for i := 0; i < len(buf); {
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// One word per loop
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for i < len(buf) && white(buf[i]) {
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i++
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}
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if i == len(buf) {
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break
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}
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// Got a word
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start := i
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if isQuote(buf[i]) {
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i = endQuote(buf, i)
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if i < 0 {
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i = len(buf)
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} else {
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i++
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}
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}
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// Even with quotes, break on whitespace only. This will
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// work with e.g. {""|} and catch quoting mistakes properly.
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for i < len(buf) && !white(buf[i]) {
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i++
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}
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s = append(s, string(buf[start:i]))
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}
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return s
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}
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// Analyze an item and return its token type and, if it's an action item, an array of
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// its constituent words.
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func (t *Template) analyze(item []byte) (tok int, w []string) {
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// item is known to be non-empty
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if !equal(item, 0, t.ldelim) { // doesn't start with left delimiter
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tok = tokText
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return
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}
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if !equal(item, len(item)-len(t.rdelim), t.rdelim) { // doesn't end with right delimiter
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t.parseError("internal error: unmatched opening delimiter") // lexing should prevent this
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return
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}
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if len(item) <= len(t.ldelim)+len(t.rdelim) { // no contents
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t.parseError("empty directive")
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return
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}
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// Comment
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if item[len(t.ldelim)] == '#' {
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tok = tokComment
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return
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}
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// Split into words
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w = words(item[len(t.ldelim) : len(item)-len(t.rdelim)]) // drop final delimiter
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if len(w) == 0 {
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t.parseError("empty directive")
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return
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}
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first := w[0]
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if first[0] != '.' {
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tok = tokVariable
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return
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}
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if len(first) > 1 && first[1] >= '0' && first[1] <= '9' {
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// Must be a float.
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tok = tokVariable
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return
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}
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switch first {
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case ".meta-left", ".meta-right", ".space", ".tab":
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tok = tokLiteral
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return
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case ".or":
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tok = tokOr
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return
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case ".end":
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tok = tokEnd
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return
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case ".section":
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if len(w) != 2 {
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t.parseError("incorrect fields for .section: %s", item)
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return
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}
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tok = tokSection
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return
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case ".repeated":
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if len(w) != 3 || w[1] != "section" {
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t.parseError("incorrect fields for .repeated: %s", item)
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return
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}
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tok = tokRepeated
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return
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case ".alternates":
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if len(w) != 2 || w[1] != "with" {
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t.parseError("incorrect fields for .alternates: %s", item)
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return
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}
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tok = tokAlternates
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return
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}
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t.parseError("bad directive: %s", item)
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return
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}
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// formatter returns the Formatter with the given name in the Template, or nil if none exists.
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func (t *Template) formatter(name string) func(io.Writer, string, ...interface{}) {
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if t.fmap != nil {
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if fn := t.fmap[name]; fn != nil {
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return fn
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}
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}
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return builtins[name]
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}
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// -- Parsing
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// Allocate a new variable-evaluation element.
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func (t *Template) newVariable(words []string) *variableElement {
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// After the final space-separated argument, formatters may be specified separated
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// by pipe symbols, for example: {a b c|d|e}
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// Until we learn otherwise, formatters contains a single name: "", the default formatter.
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formatters := []string{""}
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lastWord := words[len(words)-1]
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bar := strings.IndexRune(lastWord, '|')
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if bar >= 0 {
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words[len(words)-1] = lastWord[0:bar]
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formatters = strings.Split(lastWord[bar+1:], "|", -1)
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}
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args := make([]interface{}, len(words))
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// Build argument list, processing any literals
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for i, word := range words {
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var lerr os.Error
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switch word[0] {
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case '"', '`', '\'':
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v, err := strconv.Unquote(word)
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if err == nil && word[0] == '\'' {
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args[i] = []int(v)[0]
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} else {
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args[i], lerr = v, err
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}
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case '.', '+', '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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v, err := strconv.Btoi64(word, 0)
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if err == nil {
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args[i] = v
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} else {
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v, err := strconv.Atof64(word)
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args[i], lerr = v, err
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}
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default:
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args[i] = fieldName(word)
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}
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if lerr != nil {
|
|
t.parseError("invalid literal: %q: %s", word, lerr)
|
|
}
|
|
}
|
|
|
|
// We could remember the function address here and avoid the lookup later,
|
|
// but it's more dynamic to let the user change the map contents underfoot.
|
|
// We do require the name to be present, though.
|
|
|
|
// Is it in user-supplied map?
|
|
for _, f := range formatters {
|
|
if t.formatter(f) == nil {
|
|
t.parseError("unknown formatter: %q", f)
|
|
}
|
|
}
|
|
|
|
return &variableElement{t.linenum, args, formatters}
|
|
}
|
|
|
|
// Grab the next item. If it's simple, just append it to the template.
|
|
// Otherwise return its details.
|
|
func (t *Template) parseSimple(item []byte) (done bool, tok int, w []string) {
|
|
tok, w = t.analyze(item)
|
|
done = true // assume for simplicity
|
|
switch tok {
|
|
case tokComment:
|
|
return
|
|
case tokText:
|
|
t.elems.Push(&textElement{item})
|
|
return
|
|
case tokLiteral:
|
|
switch w[0] {
|
|
case ".meta-left":
|
|
t.elems.Push(&literalElement{t.ldelim})
|
|
case ".meta-right":
|
|
t.elems.Push(&literalElement{t.rdelim})
|
|
case ".space":
|
|
t.elems.Push(&literalElement{space})
|
|
case ".tab":
|
|
t.elems.Push(&literalElement{tab})
|
|
default:
|
|
t.parseError("internal error: unknown literal: %s", w[0])
|
|
}
|
|
return
|
|
case tokVariable:
|
|
t.elems.Push(t.newVariable(w))
|
|
return
|
|
}
|
|
return false, tok, w
|
|
}
|
|
|
|
// parseRepeated and parseSection are mutually recursive
|
|
|
|
func (t *Template) parseRepeated(words []string) *repeatedElement {
|
|
r := new(repeatedElement)
|
|
t.elems.Push(r)
|
|
r.linenum = t.linenum
|
|
r.field = words[2]
|
|
// Scan section, collecting true and false (.or) blocks.
|
|
r.start = t.elems.Len()
|
|
r.or = -1
|
|
r.altstart = -1
|
|
r.altend = -1
|
|
Loop:
|
|
for {
|
|
item := t.nextItem()
|
|
if len(item) == 0 {
|
|
t.parseError("missing .end for .repeated section")
|
|
break
|
|
}
|
|
done, tok, w := t.parseSimple(item)
|
|
if done {
|
|
continue
|
|
}
|
|
switch tok {
|
|
case tokEnd:
|
|
break Loop
|
|
case tokOr:
|
|
if r.or >= 0 {
|
|
t.parseError("extra .or in .repeated section")
|
|
break Loop
|
|
}
|
|
r.altend = t.elems.Len()
|
|
r.or = t.elems.Len()
|
|
case tokSection:
|
|
t.parseSection(w)
|
|
case tokRepeated:
|
|
t.parseRepeated(w)
|
|
case tokAlternates:
|
|
if r.altstart >= 0 {
|
|
t.parseError("extra .alternates in .repeated section")
|
|
break Loop
|
|
}
|
|
if r.or >= 0 {
|
|
t.parseError(".alternates inside .or block in .repeated section")
|
|
break Loop
|
|
}
|
|
r.altstart = t.elems.Len()
|
|
default:
|
|
t.parseError("internal error: unknown repeated section item: %s", item)
|
|
break Loop
|
|
}
|
|
}
|
|
if r.altend < 0 {
|
|
r.altend = t.elems.Len()
|
|
}
|
|
r.end = t.elems.Len()
|
|
return r
|
|
}
|
|
|
|
func (t *Template) parseSection(words []string) *sectionElement {
|
|
s := new(sectionElement)
|
|
t.elems.Push(s)
|
|
s.linenum = t.linenum
|
|
s.field = words[1]
|
|
// Scan section, collecting true and false (.or) blocks.
|
|
s.start = t.elems.Len()
|
|
s.or = -1
|
|
Loop:
|
|
for {
|
|
item := t.nextItem()
|
|
if len(item) == 0 {
|
|
t.parseError("missing .end for .section")
|
|
break
|
|
}
|
|
done, tok, w := t.parseSimple(item)
|
|
if done {
|
|
continue
|
|
}
|
|
switch tok {
|
|
case tokEnd:
|
|
break Loop
|
|
case tokOr:
|
|
if s.or >= 0 {
|
|
t.parseError("extra .or in .section")
|
|
break Loop
|
|
}
|
|
s.or = t.elems.Len()
|
|
case tokSection:
|
|
t.parseSection(w)
|
|
case tokRepeated:
|
|
t.parseRepeated(w)
|
|
case tokAlternates:
|
|
t.parseError(".alternates not in .repeated")
|
|
default:
|
|
t.parseError("internal error: unknown section item: %s", item)
|
|
}
|
|
}
|
|
s.end = t.elems.Len()
|
|
return s
|
|
}
|
|
|
|
func (t *Template) parse() {
|
|
for {
|
|
item := t.nextItem()
|
|
if len(item) == 0 {
|
|
break
|
|
}
|
|
done, tok, w := t.parseSimple(item)
|
|
if done {
|
|
continue
|
|
}
|
|
switch tok {
|
|
case tokOr, tokEnd, tokAlternates:
|
|
t.parseError("unexpected %s", w[0])
|
|
case tokSection:
|
|
t.parseSection(w)
|
|
case tokRepeated:
|
|
t.parseRepeated(w)
|
|
default:
|
|
t.parseError("internal error: bad directive in parse: %s", item)
|
|
}
|
|
}
|
|
}
|
|
|
|
// -- Execution
|
|
|
|
// Evaluate interfaces and pointers looking for a value that can look up the name, via a
|
|
// struct field, method, or map key, and return the result of the lookup.
|
|
func (t *Template) lookup(st *state, v reflect.Value, name string) reflect.Value {
|
|
for v.IsValid() {
|
|
typ := v.Type()
|
|
if n := v.Type().NumMethod(); n > 0 {
|
|
for i := 0; i < n; i++ {
|
|
m := typ.Method(i)
|
|
mtyp := m.Type
|
|
if m.Name == name && mtyp.NumIn() == 1 && mtyp.NumOut() == 1 {
|
|
if !isExported(name) {
|
|
t.execError(st, t.linenum, "name not exported: %s in type %s", name, st.data.Type())
|
|
}
|
|
return v.Method(i).Call(nil)[0]
|
|
}
|
|
}
|
|
}
|
|
switch av := v; av.Kind() {
|
|
case reflect.Ptr:
|
|
v = av.Elem()
|
|
case reflect.Interface:
|
|
v = av.Elem()
|
|
case reflect.Struct:
|
|
if !isExported(name) {
|
|
t.execError(st, t.linenum, "name not exported: %s in type %s", name, st.data.Type())
|
|
}
|
|
return av.FieldByName(name)
|
|
case reflect.Map:
|
|
if v := av.MapIndex(reflect.ValueOf(name)); v.IsValid() {
|
|
return v
|
|
}
|
|
return reflect.Zero(typ.Elem())
|
|
default:
|
|
return reflect.Value{}
|
|
}
|
|
}
|
|
return v
|
|
}
|
|
|
|
// indirectPtr returns the item numLevels levels of indirection below the value.
|
|
// It is forgiving: if the value is not a pointer, it returns it rather than giving
|
|
// an error. If the pointer is nil, it is returned as is.
|
|
func indirectPtr(v reflect.Value, numLevels int) reflect.Value {
|
|
for i := numLevels; v.IsValid() && i > 0; i++ {
|
|
if p := v; p.Kind() == reflect.Ptr {
|
|
if p.IsNil() {
|
|
return v
|
|
}
|
|
v = p.Elem()
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
return v
|
|
}
|
|
|
|
// Walk v through pointers and interfaces, extracting the elements within.
|
|
func indirect(v reflect.Value) reflect.Value {
|
|
loop:
|
|
for v.IsValid() {
|
|
switch av := v; av.Kind() {
|
|
case reflect.Ptr:
|
|
v = av.Elem()
|
|
case reflect.Interface:
|
|
v = av.Elem()
|
|
default:
|
|
break loop
|
|
}
|
|
}
|
|
return v
|
|
}
|
|
|
|
// If the data for this template is a struct, find the named variable.
|
|
// Names of the form a.b.c are walked down the data tree.
|
|
// The special name "@" (the "cursor") denotes the current data.
|
|
// The value coming in (st.data) might need indirecting to reach
|
|
// a struct while the return value is not indirected - that is,
|
|
// it represents the actual named field. Leading stars indicate
|
|
// levels of indirection to be applied to the value.
|
|
func (t *Template) findVar(st *state, s string) reflect.Value {
|
|
data := st.data
|
|
flattenedName := strings.TrimLeft(s, "*")
|
|
numStars := len(s) - len(flattenedName)
|
|
s = flattenedName
|
|
if s == "@" {
|
|
return indirectPtr(data, numStars)
|
|
}
|
|
for _, elem := range strings.Split(s, ".", -1) {
|
|
// Look up field; data must be a struct or map.
|
|
data = t.lookup(st, data, elem)
|
|
if !data.IsValid() {
|
|
return reflect.Value{}
|
|
}
|
|
}
|
|
return indirectPtr(data, numStars)
|
|
}
|
|
|
|
// Is there no data to look at?
|
|
func empty(v reflect.Value) bool {
|
|
v = indirect(v)
|
|
if !v.IsValid() {
|
|
return true
|
|
}
|
|
switch v.Kind() {
|
|
case reflect.Bool:
|
|
return v.Bool() == false
|
|
case reflect.String:
|
|
return v.String() == ""
|
|
case reflect.Struct:
|
|
return false
|
|
case reflect.Map:
|
|
return false
|
|
case reflect.Array:
|
|
return v.Len() == 0
|
|
case reflect.Slice:
|
|
return v.Len() == 0
|
|
}
|
|
return false
|
|
}
|
|
|
|
// Look up a variable or method, up through the parent if necessary.
|
|
func (t *Template) varValue(name string, st *state) reflect.Value {
|
|
field := t.findVar(st, name)
|
|
if !field.IsValid() {
|
|
if st.parent == nil {
|
|
t.execError(st, t.linenum, "name not found: %s in type %s", name, st.data.Type())
|
|
}
|
|
return t.varValue(name, st.parent)
|
|
}
|
|
return field
|
|
}
|
|
|
|
func (t *Template) format(wr io.Writer, fmt string, val []interface{}, v *variableElement, st *state) {
|
|
fn := t.formatter(fmt)
|
|
if fn == nil {
|
|
t.execError(st, v.linenum, "missing formatter %s for variable", fmt)
|
|
}
|
|
fn(wr, fmt, val...)
|
|
}
|
|
|
|
// Evaluate a variable, looking up through the parent if necessary.
|
|
// If it has a formatter attached ({var|formatter}) run that too.
|
|
func (t *Template) writeVariable(v *variableElement, st *state) {
|
|
// Resolve field names
|
|
val := make([]interface{}, len(v.args))
|
|
for i, arg := range v.args {
|
|
if name, ok := arg.(fieldName); ok {
|
|
val[i] = t.varValue(string(name), st).Interface()
|
|
} else {
|
|
val[i] = arg
|
|
}
|
|
}
|
|
for i, fmt := range v.fmts[:len(v.fmts)-1] {
|
|
b := &st.buf[i&1]
|
|
b.Reset()
|
|
t.format(b, fmt, val, v, st)
|
|
val = val[0:1]
|
|
val[0] = b.Bytes()
|
|
}
|
|
t.format(st.wr, v.fmts[len(v.fmts)-1], val, v, st)
|
|
}
|
|
|
|
// Execute element i. Return next index to execute.
|
|
func (t *Template) executeElement(i int, st *state) int {
|
|
switch elem := t.elems.At(i).(type) {
|
|
case *textElement:
|
|
st.wr.Write(elem.text)
|
|
return i + 1
|
|
case *literalElement:
|
|
st.wr.Write(elem.text)
|
|
return i + 1
|
|
case *variableElement:
|
|
t.writeVariable(elem, st)
|
|
return i + 1
|
|
case *sectionElement:
|
|
t.executeSection(elem, st)
|
|
return elem.end
|
|
case *repeatedElement:
|
|
t.executeRepeated(elem, st)
|
|
return elem.end
|
|
}
|
|
e := t.elems.At(i)
|
|
t.execError(st, 0, "internal error: bad directive in execute: %v %T\n", reflect.ValueOf(e).Interface(), e)
|
|
return 0
|
|
}
|
|
|
|
// Execute the template.
|
|
func (t *Template) execute(start, end int, st *state) {
|
|
for i := start; i < end; {
|
|
i = t.executeElement(i, st)
|
|
}
|
|
}
|
|
|
|
// Execute a .section
|
|
func (t *Template) executeSection(s *sectionElement, st *state) {
|
|
// Find driver data for this section. It must be in the current struct.
|
|
field := t.varValue(s.field, st)
|
|
if !field.IsValid() {
|
|
t.execError(st, s.linenum, ".section: cannot find field %s in %s", s.field, st.data.Type())
|
|
}
|
|
st = st.clone(field)
|
|
start, end := s.start, s.or
|
|
if !empty(field) {
|
|
// Execute the normal block.
|
|
if end < 0 {
|
|
end = s.end
|
|
}
|
|
} else {
|
|
// Execute the .or block. If it's missing, do nothing.
|
|
start, end = s.or, s.end
|
|
if start < 0 {
|
|
return
|
|
}
|
|
}
|
|
for i := start; i < end; {
|
|
i = t.executeElement(i, st)
|
|
}
|
|
}
|
|
|
|
// Return the result of calling the Iter method on v, or nil.
|
|
func iter(v reflect.Value) reflect.Value {
|
|
for j := 0; j < v.Type().NumMethod(); j++ {
|
|
mth := v.Type().Method(j)
|
|
fv := v.Method(j)
|
|
ft := fv.Type()
|
|
// TODO(rsc): NumIn() should return 0 here, because ft is from a curried FuncValue.
|
|
if mth.Name != "Iter" || ft.NumIn() != 1 || ft.NumOut() != 1 {
|
|
continue
|
|
}
|
|
ct := ft.Out(0)
|
|
if ct.Kind() != reflect.Chan ||
|
|
ct.ChanDir()&reflect.RecvDir == 0 {
|
|
continue
|
|
}
|
|
return fv.Call(nil)[0]
|
|
}
|
|
return reflect.Value{}
|
|
}
|
|
|
|
// Execute a .repeated section
|
|
func (t *Template) executeRepeated(r *repeatedElement, st *state) {
|
|
// Find driver data for this section. It must be in the current struct.
|
|
field := t.varValue(r.field, st)
|
|
if !field.IsValid() {
|
|
t.execError(st, r.linenum, ".repeated: cannot find field %s in %s", r.field, st.data.Type())
|
|
}
|
|
field = indirect(field)
|
|
|
|
start, end := r.start, r.or
|
|
if end < 0 {
|
|
end = r.end
|
|
}
|
|
if r.altstart >= 0 {
|
|
end = r.altstart
|
|
}
|
|
first := true
|
|
|
|
// Code common to all the loops.
|
|
loopBody := func(newst *state) {
|
|
// .alternates between elements
|
|
if !first && r.altstart >= 0 {
|
|
for i := r.altstart; i < r.altend; {
|
|
i = t.executeElement(i, newst)
|
|
}
|
|
}
|
|
first = false
|
|
for i := start; i < end; {
|
|
i = t.executeElement(i, newst)
|
|
}
|
|
}
|
|
|
|
if array := field; array.Kind() == reflect.Array || array.Kind() == reflect.Slice {
|
|
for j := 0; j < array.Len(); j++ {
|
|
loopBody(st.clone(array.Index(j)))
|
|
}
|
|
} else if m := field; m.Kind() == reflect.Map {
|
|
for _, key := range m.MapKeys() {
|
|
loopBody(st.clone(m.MapIndex(key)))
|
|
}
|
|
} else if ch := iter(field); ch.IsValid() {
|
|
for {
|
|
e, ok := ch.Recv()
|
|
if !ok {
|
|
break
|
|
}
|
|
loopBody(st.clone(e))
|
|
}
|
|
} else {
|
|
t.execError(st, r.linenum, ".repeated: cannot repeat %s (type %s)",
|
|
r.field, field.Type())
|
|
}
|
|
|
|
if first {
|
|
// Empty. Execute the .or block, once. If it's missing, do nothing.
|
|
start, end := r.or, r.end
|
|
if start >= 0 {
|
|
newst := st.clone(field)
|
|
for i := start; i < end; {
|
|
i = t.executeElement(i, newst)
|
|
}
|
|
}
|
|
return
|
|
}
|
|
}
|
|
|
|
// A valid delimiter must contain no white space and be non-empty.
|
|
func validDelim(d []byte) bool {
|
|
if len(d) == 0 {
|
|
return false
|
|
}
|
|
for _, c := range d {
|
|
if white(c) {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// checkError is a deferred function to turn a panic with type *Error into a plain error return.
|
|
// Other panics are unexpected and so are re-enabled.
|
|
func checkError(error *os.Error) {
|
|
if v := recover(); v != nil {
|
|
if e, ok := v.(*Error); ok {
|
|
*error = e
|
|
} else {
|
|
// runtime errors should crash
|
|
panic(v)
|
|
}
|
|
}
|
|
}
|
|
|
|
// -- Public interface
|
|
|
|
// Parse initializes a Template by parsing its definition. The string
|
|
// s contains the template text. If any errors occur, Parse returns
|
|
// the error.
|
|
func (t *Template) Parse(s string) (err os.Error) {
|
|
if t.elems == nil {
|
|
return &Error{1, "template not allocated with New"}
|
|
}
|
|
if !validDelim(t.ldelim) || !validDelim(t.rdelim) {
|
|
return &Error{1, fmt.Sprintf("bad delimiter strings %q %q", t.ldelim, t.rdelim)}
|
|
}
|
|
defer checkError(&err)
|
|
t.buf = []byte(s)
|
|
t.p = 0
|
|
t.linenum = 1
|
|
t.parse()
|
|
return nil
|
|
}
|
|
|
|
// ParseFile is like Parse but reads the template definition from the
|
|
// named file.
|
|
func (t *Template) ParseFile(filename string) (err os.Error) {
|
|
b, err := ioutil.ReadFile(filename)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return t.Parse(string(b))
|
|
}
|
|
|
|
// Execute applies a parsed template to the specified data object,
|
|
// generating output to wr.
|
|
func (t *Template) Execute(wr io.Writer, data interface{}) (err os.Error) {
|
|
// Extract the driver data.
|
|
val := reflect.ValueOf(data)
|
|
defer checkError(&err)
|
|
t.p = 0
|
|
t.execute(0, t.elems.Len(), &state{parent: nil, data: val, wr: wr})
|
|
return nil
|
|
}
|
|
|
|
// SetDelims sets the left and right delimiters for operations in the
|
|
// template. They are validated during parsing. They could be
|
|
// validated here but it's better to keep the routine simple. The
|
|
// delimiters are very rarely invalid and Parse has the necessary
|
|
// error-handling interface already.
|
|
func (t *Template) SetDelims(left, right string) {
|
|
t.ldelim = []byte(left)
|
|
t.rdelim = []byte(right)
|
|
}
|
|
|
|
// Parse creates a Template with default parameters (such as {} for
|
|
// metacharacters). The string s contains the template text while
|
|
// the formatter map fmap, which may be nil, defines auxiliary functions
|
|
// for formatting variables. The template is returned. If any errors
|
|
// occur, err will be non-nil.
|
|
func Parse(s string, fmap FormatterMap) (t *Template, err os.Error) {
|
|
t = New(fmap)
|
|
err = t.Parse(s)
|
|
if err != nil {
|
|
t = nil
|
|
}
|
|
return
|
|
}
|
|
|
|
// ParseFile is a wrapper function that creates a Template with default
|
|
// parameters (such as {} for metacharacters). The filename identifies
|
|
// a file containing the template text, while the formatter map fmap, which
|
|
// may be nil, defines auxiliary functions for formatting variables.
|
|
// The template is returned. If any errors occur, err will be non-nil.
|
|
func ParseFile(filename string, fmap FormatterMap) (t *Template, err os.Error) {
|
|
b, err := ioutil.ReadFile(filename)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return Parse(string(b), fmap)
|
|
}
|
|
|
|
// MustParse is like Parse but panics if the template cannot be parsed.
|
|
func MustParse(s string, fmap FormatterMap) *Template {
|
|
t, err := Parse(s, fmap)
|
|
if err != nil {
|
|
panic("template.MustParse error: " + err.String())
|
|
}
|
|
return t
|
|
}
|
|
|
|
// MustParseFile is like ParseFile but panics if the file cannot be read
|
|
// or the template cannot be parsed.
|
|
func MustParseFile(filename string, fmap FormatterMap) *Template {
|
|
b, err := ioutil.ReadFile(filename)
|
|
if err != nil {
|
|
panic("template.MustParseFile error: " + err.String())
|
|
}
|
|
return MustParse(string(b), fmap)
|
|
}
|