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Diffstat (limited to 'src/cmd/godoc/format.go')
| -rw-r--r-- | src/cmd/godoc/format.go | 373 |
1 files changed, 0 insertions, 373 deletions
diff --git a/src/cmd/godoc/format.go b/src/cmd/godoc/format.go deleted file mode 100644 index 7e6470846..000000000 --- a/src/cmd/godoc/format.go +++ /dev/null @@ -1,373 +0,0 @@ -// Copyright 2011 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. - -// This file implements FormatSelections and FormatText. -// FormatText is used to HTML-format Go and non-Go source -// text with line numbers and highlighted sections. It is -// built on top of FormatSelections, a generic formatter -// for "selected" text. - -package main - -import ( - "fmt" - "go/scanner" - "go/token" - "io" - "regexp" - "strconv" - "template" -) - - -// ---------------------------------------------------------------------------- -// Implementation of FormatSelections - -// A Selection is a function returning offset pairs []int{a, b} -// describing consecutive non-overlapping text segments [a, b). -// If there are no more segments, a Selection must return nil. -// -// TODO It's more efficient to return a pair (a, b int) instead -// of creating lots of slices. Need to determine how to -// indicate the end of a Selection. -// -type Selection func() []int - - -// A LinkWriter writes some start or end "tag" to w for the text offset offs. -// It is called by FormatSelections at the start or end of each link segment. -// -type LinkWriter func(w io.Writer, offs int, start bool) - - -// A SegmentWriter formats a text according to selections and writes it to w. -// The selections parameter is a bit set indicating which selections provided -// to FormatSelections overlap with the text segment: If the n'th bit is set -// in selections, the n'th selection provided to FormatSelections is overlapping -// with the text. -// -type SegmentWriter func(w io.Writer, text []byte, selections int) - - -// FormatSelections takes a text and writes it to w using link and segment -// writers lw and sw as follows: lw is invoked for consecutive segment starts -// and ends as specified through the links selection, and sw is invoked for -// consecutive segments of text overlapped by the same selections as specified -// by selections. The link writer lw may be nil, in which case the links -// Selection is ignored. -// -func FormatSelections(w io.Writer, text []byte, lw LinkWriter, links Selection, sw SegmentWriter, selections ...Selection) { - if lw != nil { - selections = append(selections, links) - } - - // compute the sequence of consecutive segment changes - changes := newMerger(selections) - - // The i'th bit in bitset indicates that the text - // at the current offset is covered by selections[i]. - bitset := 0 - lastOffs := 0 - - // Text segments are written in a delayed fashion - // such that consecutive segments belonging to the - // same selection can be combined (peephole optimization). - // last describes the last segment which has not yet been written. - var last struct { - begin, end int // valid if begin < end - bitset int - } - - // flush writes the last delayed text segment - flush := func() { - if last.begin < last.end { - sw(w, text[last.begin:last.end], last.bitset) - } - last.begin = last.end // invalidate last - } - - // segment runs the segment [lastOffs, end) with the selection - // indicated by bitset through the segment peephole optimizer. - segment := func(end int) { - if lastOffs < end { // ignore empty segments - if last.end != lastOffs || last.bitset != bitset { - // the last segment is not adjacent to or - // differs from the new one - flush() - // start a new segment - last.begin = lastOffs - } - last.end = end - last.bitset = bitset - } - } - - for { - // get the next segment change - index, offs, start := changes.next() - if index < 0 || offs > len(text) { - // no more segment changes or the next change - // is past the end of the text - we're done - break - } - // determine the kind of segment change - if index == len(selections)-1 { - // we have a link segment change: - // format the previous selection segment, write the - // link tag and start a new selection segment - segment(offs) - flush() - lastOffs = offs - lw(w, offs, start) - } else { - // we have a selection change: - // format the previous selection segment, determine - // the new selection bitset and start a new segment - segment(offs) - lastOffs = offs - mask := 1 << uint(index) - if start { - bitset |= mask - } else { - bitset &^= mask - } - } - } - segment(len(text)) - flush() -} - - -// A merger merges a slice of Selections and produces a sequence of -// consecutive segment change events through repeated next() calls. -// -type merger struct { - selections []Selection - segments [][]int // segments[i] is the next segment of selections[i] -} - - -const infinity int = 2e9 - -func newMerger(selections []Selection) *merger { - segments := make([][]int, len(selections)) - for i, sel := range selections { - segments[i] = []int{infinity, infinity} - if sel != nil { - if seg := sel(); seg != nil { - segments[i] = seg - } - } - } - return &merger{selections, segments} -} - - -// next returns the next segment change: index specifies the Selection -// to which the segment belongs, offs is the segment start or end offset -// as determined by the start value. If there are no more segment changes, -// next returns an index value < 0. -// -func (m *merger) next() (index, offs int, start bool) { - // find the next smallest offset where a segment starts or ends - offs = infinity - index = -1 - for i, seg := range m.segments { - switch { - case seg[0] < offs: - offs = seg[0] - index = i - start = true - case seg[1] < offs: - offs = seg[1] - index = i - start = false - } - } - if index < 0 { - // no offset found => all selections merged - return - } - // offset found - it's either the start or end offset but - // either way it is ok to consume the start offset: set it - // to infinity so it won't be considered in the following - // next call - m.segments[index][0] = infinity - if start { - return - } - // end offset found - consume it - m.segments[index][1] = infinity - // advance to the next segment for that selection - seg := m.selections[index]() - if seg == nil { - return - } - m.segments[index] = seg - return -} - - -// ---------------------------------------------------------------------------- -// Implementation of FormatText - -// lineSelection returns the line segments for text as a Selection. -func lineSelection(text []byte) Selection { - i, j := 0, 0 - return func() (seg []int) { - // find next newline, if any - for j < len(text) { - j++ - if text[j-1] == '\n' { - break - } - } - if i < j { - // text[i:j] constitutes a line - seg = []int{i, j} - i = j - } - return - } -} - - -// commentSelection returns the sequence of consecutive comments -// in the Go src text as a Selection. -// -func commentSelection(src []byte) Selection { - var s scanner.Scanner - fset := token.NewFileSet() - file := fset.AddFile("", fset.Base(), len(src)) - s.Init(file, src, nil, scanner.ScanComments+scanner.InsertSemis) - return func() (seg []int) { - for { - pos, tok, lit := s.Scan() - if tok == token.EOF { - break - } - offs := file.Offset(pos) - if tok == token.COMMENT { - seg = []int{offs, offs + len(lit)} - break - } - } - return - } -} - - -// makeSelection is a helper function to make a Selection from a slice of pairs. -func makeSelection(matches [][]int) Selection { - return func() (seg []int) { - if len(matches) > 0 { - seg = matches[0] - matches = matches[1:] - } - return - } -} - - -// regexpSelection computes the Selection for the regular expression expr in text. -func regexpSelection(text []byte, expr string) Selection { - var matches [][]int - if rx, err := regexp.Compile(expr); err == nil { - matches = rx.FindAllIndex(text, -1) - } - return makeSelection(matches) -} - - -var selRx = regexp.MustCompile(`^([0-9]+):([0-9]+)`) - -// rangeSelection computes the Selection for a text range described -// by the argument str; the range description must match the selRx -// regular expression. -// -func rangeSelection(str string) Selection { - m := selRx.FindStringSubmatch(str) - if len(m) >= 2 { - from, _ := strconv.Atoi(m[1]) - to, _ := strconv.Atoi(m[2]) - if from < to { - return makeSelection([][]int{{from, to}}) - } - } - return nil -} - - -// Span tags for all the possible selection combinations that may -// be generated by FormatText. Selections are indicated by a bitset, -// and the value of the bitset specifies the tag to be used. -// -// bit 0: comments -// bit 1: highlights -// bit 2: selections -// -var startTags = [][]byte{ - /* 000 */ []byte(``), - /* 001 */ []byte(`<span class="comment">`), - /* 010 */ []byte(`<span class="highlight">`), - /* 011 */ []byte(`<span class="highlight-comment">`), - /* 100 */ []byte(`<span class="selection">`), - /* 101 */ []byte(`<span class="selection-comment">`), - /* 110 */ []byte(`<span class="selection-highlight">`), - /* 111 */ []byte(`<span class="selection-highlight-comment">`), -} - -var endTag = []byte(`</span>`) - - -func selectionTag(w io.Writer, text []byte, selections int) { - if selections < len(startTags) { - if tag := startTags[selections]; len(tag) > 0 { - w.Write(tag) - template.HTMLEscape(w, text) - w.Write(endTag) - return - } - } - template.HTMLEscape(w, text) -} - - -// FormatText HTML-escapes text and writes it to w. -// Consecutive text segments are wrapped in HTML spans (with tags as -// defined by startTags and endTag) as follows: -// -// - if line >= 0, line number (ln) spans are inserted before each line, -// starting with the value of line -// - if the text is Go source, comments get the "comment" span class -// - each occurrence of the regular expression pattern gets the "highlight" -// span class -// - text segments covered by selection get the "selection" span class -// -// Comments, highlights, and selections may overlap arbitrarily; the respective -// HTML span classes are specified in the startTags variable. -// -func FormatText(w io.Writer, text []byte, line int, goSource bool, pattern string, selection Selection) { - var comments, highlights Selection - if goSource { - comments = commentSelection(text) - } - if pattern != "" { - highlights = regexpSelection(text, pattern) - } - if line >= 0 || comments != nil || highlights != nil || selection != nil { - var lineTag LinkWriter - if line >= 0 { - lineTag = func(w io.Writer, _ int, start bool) { - if start { - fmt.Fprintf(w, "<a id=\"L%d\"></a><span class=\"ln\">%6d</span>\t", line, line) - line++ - } - } - } - FormatSelections(w, text, lineTag, lineSelection(text), selectionTag, comments, highlights, selection) - } else { - template.HTMLEscape(w, text) - } -} |