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-rw-r--r--src/pkg/go/printer/printer.go1292
1 files changed, 0 insertions, 1292 deletions
diff --git a/src/pkg/go/printer/printer.go b/src/pkg/go/printer/printer.go
deleted file mode 100644
index 280c697a0..000000000
--- a/src/pkg/go/printer/printer.go
+++ /dev/null
@@ -1,1292 +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 printer implements printing of AST nodes.
-package printer
-
-import (
- "fmt"
- "go/ast"
- "go/token"
- "io"
- "os"
- "strconv"
- "strings"
- "text/tabwriter"
- "unicode"
-)
-
-const (
- maxNewlines = 2 // max. number of newlines between source text
- debug = false // enable for debugging
- infinity = 1 << 30
-)
-
-type whiteSpace byte
-
-const (
- ignore = whiteSpace(0)
- blank = whiteSpace(' ')
- vtab = whiteSpace('\v')
- newline = whiteSpace('\n')
- formfeed = whiteSpace('\f')
- indent = whiteSpace('>')
- unindent = whiteSpace('<')
-)
-
-// A pmode value represents the current printer mode.
-type pmode int
-
-const (
- noExtraBlank pmode = 1 << iota // disables extra blank after /*-style comment
- noExtraLinebreak // disables extra line break after /*-style comment
-)
-
-type commentInfo struct {
- cindex int // current comment index
- comment *ast.CommentGroup // = printer.comments[cindex]; or nil
- commentOffset int // = printer.posFor(printer.comments[cindex].List[0].Pos()).Offset; or infinity
- commentNewline bool // true if the comment group contains newlines
-}
-
-type printer struct {
- // Configuration (does not change after initialization)
- Config
- fset *token.FileSet
-
- // Current state
- output []byte // raw printer result
- indent int // current indentation
- mode pmode // current printer mode
- impliedSemi bool // if set, a linebreak implies a semicolon
- lastTok token.Token // last token printed (token.ILLEGAL if it's whitespace)
- prevOpen token.Token // previous non-brace "open" token (, [, or token.ILLEGAL
- wsbuf []whiteSpace // delayed white space
-
- // Positions
- // The out position differs from the pos position when the result
- // formatting differs from the source formatting (in the amount of
- // white space). If there's a difference and SourcePos is set in
- // ConfigMode, //line comments are used in the output to restore
- // original source positions for a reader.
- pos token.Position // current position in AST (source) space
- out token.Position // current position in output space
- last token.Position // value of pos after calling writeString
- linePtr *int // if set, record out.Line for the next token in *linePtr
-
- // The list of all source comments, in order of appearance.
- comments []*ast.CommentGroup // may be nil
- useNodeComments bool // if not set, ignore lead and line comments of nodes
-
- // Information about p.comments[p.cindex]; set up by nextComment.
- commentInfo
-
- // Cache of already computed node sizes.
- nodeSizes map[ast.Node]int
-
- // Cache of most recently computed line position.
- cachedPos token.Pos
- cachedLine int // line corresponding to cachedPos
-}
-
-func (p *printer) init(cfg *Config, fset *token.FileSet, nodeSizes map[ast.Node]int) {
- p.Config = *cfg
- p.fset = fset
- p.pos = token.Position{Line: 1, Column: 1}
- p.out = token.Position{Line: 1, Column: 1}
- p.wsbuf = make([]whiteSpace, 0, 16) // whitespace sequences are short
- p.nodeSizes = nodeSizes
- p.cachedPos = -1
-}
-
-func (p *printer) internalError(msg ...interface{}) {
- if debug {
- fmt.Print(p.pos.String() + ": ")
- fmt.Println(msg...)
- panic("go/printer")
- }
-}
-
-// commentsHaveNewline reports whether a list of comments belonging to
-// an *ast.CommentGroup contains newlines. Because the position information
-// may only be partially correct, we also have to read the comment text.
-func (p *printer) commentsHaveNewline(list []*ast.Comment) bool {
- // len(list) > 0
- line := p.lineFor(list[0].Pos())
- for i, c := range list {
- if i > 0 && p.lineFor(list[i].Pos()) != line {
- // not all comments on the same line
- return true
- }
- if t := c.Text; len(t) >= 2 && (t[1] == '/' || strings.Contains(t, "\n")) {
- return true
- }
- }
- _ = line
- return false
-}
-
-func (p *printer) nextComment() {
- for p.cindex < len(p.comments) {
- c := p.comments[p.cindex]
- p.cindex++
- if list := c.List; len(list) > 0 {
- p.comment = c
- p.commentOffset = p.posFor(list[0].Pos()).Offset
- p.commentNewline = p.commentsHaveNewline(list)
- return
- }
- // we should not reach here (correct ASTs don't have empty
- // ast.CommentGroup nodes), but be conservative and try again
- }
- // no more comments
- p.commentOffset = infinity
-}
-
-// commentBefore returns true iff the current comment group occurs
-// before the next position in the source code and printing it does
-// not introduce implicit semicolons.
-//
-func (p *printer) commentBefore(next token.Position) bool {
- return p.commentOffset < next.Offset && (!p.impliedSemi || !p.commentNewline)
-}
-
-// commentSizeBefore returns the estimated size of the
-// comments on the same line before the next position.
-//
-func (p *printer) commentSizeBefore(next token.Position) int {
- // save/restore current p.commentInfo (p.nextComment() modifies it)
- defer func(info commentInfo) {
- p.commentInfo = info
- }(p.commentInfo)
-
- size := 0
- for p.commentBefore(next) {
- for _, c := range p.comment.List {
- size += len(c.Text)
- }
- p.nextComment()
- }
- return size
-}
-
-// recordLine records the output line number for the next non-whitespace
-// token in *linePtr. It is used to compute an accurate line number for a
-// formatted construct, independent of pending (not yet emitted) whitespace
-// or comments.
-//
-func (p *printer) recordLine(linePtr *int) {
- p.linePtr = linePtr
-}
-
-// linesFrom returns the number of output lines between the current
-// output line and the line argument, ignoring any pending (not yet
-// emitted) whitespace or comments. It is used to compute an accurate
-// size (in number of lines) for a formatted construct.
-//
-func (p *printer) linesFrom(line int) int {
- return p.out.Line - line
-}
-
-func (p *printer) posFor(pos token.Pos) token.Position {
- // not used frequently enough to cache entire token.Position
- return p.fset.Position(pos)
-}
-
-func (p *printer) lineFor(pos token.Pos) int {
- if pos != p.cachedPos {
- p.cachedPos = pos
- p.cachedLine = p.fset.Position(pos).Line
- }
- return p.cachedLine
-}
-
-// atLineBegin emits a //line comment if necessary and prints indentation.
-func (p *printer) atLineBegin(pos token.Position) {
- // write a //line comment if necessary
- if p.Config.Mode&SourcePos != 0 && pos.IsValid() && (p.out.Line != pos.Line || p.out.Filename != pos.Filename) {
- p.output = append(p.output, tabwriter.Escape) // protect '\n' in //line from tabwriter interpretation
- p.output = append(p.output, fmt.Sprintf("//line %s:%d\n", pos.Filename, pos.Line)...)
- p.output = append(p.output, tabwriter.Escape)
- // p.out must match the //line comment
- p.out.Filename = pos.Filename
- p.out.Line = pos.Line
- }
-
- // write indentation
- // use "hard" htabs - indentation columns
- // must not be discarded by the tabwriter
- n := p.Config.Indent + p.indent // include base indentation
- for i := 0; i < n; i++ {
- p.output = append(p.output, '\t')
- }
-
- // update positions
- p.pos.Offset += n
- p.pos.Column += n
- p.out.Column += n
-}
-
-// writeByte writes ch n times to p.output and updates p.pos.
-func (p *printer) writeByte(ch byte, n int) {
- if p.out.Column == 1 {
- p.atLineBegin(p.pos)
- }
-
- for i := 0; i < n; i++ {
- p.output = append(p.output, ch)
- }
-
- // update positions
- p.pos.Offset += n
- if ch == '\n' || ch == '\f' {
- p.pos.Line += n
- p.out.Line += n
- p.pos.Column = 1
- p.out.Column = 1
- return
- }
- p.pos.Column += n
- p.out.Column += n
-}
-
-// writeString writes the string s to p.output and updates p.pos, p.out,
-// and p.last. If isLit is set, s is escaped w/ tabwriter.Escape characters
-// to protect s from being interpreted by the tabwriter.
-//
-// Note: writeString is only used to write Go tokens, literals, and
-// comments, all of which must be written literally. Thus, it is correct
-// to always set isLit = true. However, setting it explicitly only when
-// needed (i.e., when we don't know that s contains no tabs or line breaks)
-// avoids processing extra escape characters and reduces run time of the
-// printer benchmark by up to 10%.
-//
-func (p *printer) writeString(pos token.Position, s string, isLit bool) {
- if p.out.Column == 1 {
- p.atLineBegin(pos)
- }
-
- if pos.IsValid() {
- // update p.pos (if pos is invalid, continue with existing p.pos)
- // Note: Must do this after handling line beginnings because
- // atLineBegin updates p.pos if there's indentation, but p.pos
- // is the position of s.
- p.pos = pos
- }
-
- if isLit {
- // Protect s such that is passes through the tabwriter
- // unchanged. Note that valid Go programs cannot contain
- // tabwriter.Escape bytes since they do not appear in legal
- // UTF-8 sequences.
- p.output = append(p.output, tabwriter.Escape)
- }
-
- if debug {
- p.output = append(p.output, fmt.Sprintf("/*%s*/", pos)...) // do not update p.pos!
- }
- p.output = append(p.output, s...)
-
- // update positions
- nlines := 0
- var li int // index of last newline; valid if nlines > 0
- for i := 0; i < len(s); i++ {
- // Go tokens cannot contain '\f' - no need to look for it
- if s[i] == '\n' {
- nlines++
- li = i
- }
- }
- p.pos.Offset += len(s)
- if nlines > 0 {
- p.pos.Line += nlines
- p.out.Line += nlines
- c := len(s) - li
- p.pos.Column = c
- p.out.Column = c
- } else {
- p.pos.Column += len(s)
- p.out.Column += len(s)
- }
-
- if isLit {
- p.output = append(p.output, tabwriter.Escape)
- }
-
- p.last = p.pos
-}
-
-// writeCommentPrefix writes the whitespace before a comment.
-// If there is any pending whitespace, it consumes as much of
-// it as is likely to help position the comment nicely.
-// pos is the comment position, next the position of the item
-// after all pending comments, prev is the previous comment in
-// a group of comments (or nil), and tok is the next token.
-//
-func (p *printer) writeCommentPrefix(pos, next token.Position, prev, comment *ast.Comment, tok token.Token) {
- if len(p.output) == 0 {
- // the comment is the first item to be printed - don't write any whitespace
- return
- }
-
- if pos.IsValid() && pos.Filename != p.last.Filename {
- // comment in a different file - separate with newlines
- p.writeByte('\f', maxNewlines)
- return
- }
-
- if pos.Line == p.last.Line && (prev == nil || prev.Text[1] != '/') {
- // comment on the same line as last item:
- // separate with at least one separator
- hasSep := false
- if prev == nil {
- // first comment of a comment group
- j := 0
- for i, ch := range p.wsbuf {
- switch ch {
- case blank:
- // ignore any blanks before a comment
- p.wsbuf[i] = ignore
- continue
- case vtab:
- // respect existing tabs - important
- // for proper formatting of commented structs
- hasSep = true
- continue
- case indent:
- // apply pending indentation
- continue
- }
- j = i
- break
- }
- p.writeWhitespace(j)
- }
- // make sure there is at least one separator
- if !hasSep {
- sep := byte('\t')
- if pos.Line == next.Line {
- // next item is on the same line as the comment
- // (which must be a /*-style comment): separate
- // with a blank instead of a tab
- sep = ' '
- }
- p.writeByte(sep, 1)
- }
-
- } else {
- // comment on a different line:
- // separate with at least one line break
- droppedLinebreak := false
- j := 0
- for i, ch := range p.wsbuf {
- switch ch {
- case blank, vtab:
- // ignore any horizontal whitespace before line breaks
- p.wsbuf[i] = ignore
- continue
- case indent:
- // apply pending indentation
- continue
- case unindent:
- // if this is not the last unindent, apply it
- // as it is (likely) belonging to the last
- // construct (e.g., a multi-line expression list)
- // and is not part of closing a block
- if i+1 < len(p.wsbuf) && p.wsbuf[i+1] == unindent {
- continue
- }
- // if the next token is not a closing }, apply the unindent
- // if it appears that the comment is aligned with the
- // token; otherwise assume the unindent is part of a
- // closing block and stop (this scenario appears with
- // comments before a case label where the comments
- // apply to the next case instead of the current one)
- if tok != token.RBRACE && pos.Column == next.Column {
- continue
- }
- case newline, formfeed:
- p.wsbuf[i] = ignore
- droppedLinebreak = prev == nil // record only if first comment of a group
- }
- j = i
- break
- }
- p.writeWhitespace(j)
-
- // determine number of linebreaks before the comment
- n := 0
- if pos.IsValid() && p.last.IsValid() {
- n = pos.Line - p.last.Line
- if n < 0 { // should never happen
- n = 0
- }
- }
-
- // at the package scope level only (p.indent == 0),
- // add an extra newline if we dropped one before:
- // this preserves a blank line before documentation
- // comments at the package scope level (issue 2570)
- if p.indent == 0 && droppedLinebreak {
- n++
- }
-
- // make sure there is at least one line break
- // if the previous comment was a line comment
- if n == 0 && prev != nil && prev.Text[1] == '/' {
- n = 1
- }
-
- if n > 0 {
- // use formfeeds to break columns before a comment;
- // this is analogous to using formfeeds to separate
- // individual lines of /*-style comments
- p.writeByte('\f', nlimit(n))
- }
- }
-}
-
-// Returns true if s contains only white space
-// (only tabs and blanks can appear in the printer's context).
-//
-func isBlank(s string) bool {
- for i := 0; i < len(s); i++ {
- if s[i] > ' ' {
- return false
- }
- }
- return true
-}
-
-// commonPrefix returns the common prefix of a and b.
-func commonPrefix(a, b string) string {
- i := 0
- for i < len(a) && i < len(b) && a[i] == b[i] && (a[i] <= ' ' || a[i] == '*') {
- i++
- }
- return a[0:i]
-}
-
-// trimRight returns s with trailing whitespace removed.
-func trimRight(s string) string {
- return strings.TrimRightFunc(s, unicode.IsSpace)
-}
-
-// stripCommonPrefix removes a common prefix from /*-style comment lines (unless no
-// comment line is indented, all but the first line have some form of space prefix).
-// The prefix is computed using heuristics such that is likely that the comment
-// contents are nicely laid out after re-printing each line using the printer's
-// current indentation.
-//
-func stripCommonPrefix(lines []string) {
- if len(lines) <= 1 {
- return // at most one line - nothing to do
- }
- // len(lines) > 1
-
- // The heuristic in this function tries to handle a few
- // common patterns of /*-style comments: Comments where
- // the opening /* and closing */ are aligned and the
- // rest of the comment text is aligned and indented with
- // blanks or tabs, cases with a vertical "line of stars"
- // on the left, and cases where the closing */ is on the
- // same line as the last comment text.
-
- // Compute maximum common white prefix of all but the first,
- // last, and blank lines, and replace blank lines with empty
- // lines (the first line starts with /* and has no prefix).
- // In case of two-line comments, consider the last line for
- // the prefix computation since otherwise the prefix would
- // be empty.
- //
- // Note that the first and last line are never empty (they
- // contain the opening /* and closing */ respectively) and
- // thus they can be ignored by the blank line check.
- var prefix string
- if len(lines) > 2 {
- first := true
- for i, line := range lines[1 : len(lines)-1] {
- switch {
- case isBlank(line):
- lines[1+i] = "" // range starts with lines[1]
- case first:
- prefix = commonPrefix(line, line)
- first = false
- default:
- prefix = commonPrefix(prefix, line)
- }
- }
- } else { // len(lines) == 2, lines cannot be blank (contain /* and */)
- line := lines[1]
- prefix = commonPrefix(line, line)
- }
-
- /*
- * Check for vertical "line of stars" and correct prefix accordingly.
- */
- lineOfStars := false
- if i := strings.Index(prefix, "*"); i >= 0 {
- // Line of stars present.
- if i > 0 && prefix[i-1] == ' ' {
- i-- // remove trailing blank from prefix so stars remain aligned
- }
- prefix = prefix[0:i]
- lineOfStars = true
- } else {
- // No line of stars present.
- // Determine the white space on the first line after the /*
- // and before the beginning of the comment text, assume two
- // blanks instead of the /* unless the first character after
- // the /* is a tab. If the first comment line is empty but
- // for the opening /*, assume up to 3 blanks or a tab. This
- // whitespace may be found as suffix in the common prefix.
- first := lines[0]
- if isBlank(first[2:]) {
- // no comment text on the first line:
- // reduce prefix by up to 3 blanks or a tab
- // if present - this keeps comment text indented
- // relative to the /* and */'s if it was indented
- // in the first place
- i := len(prefix)
- for n := 0; n < 3 && i > 0 && prefix[i-1] == ' '; n++ {
- i--
- }
- if i == len(prefix) && i > 0 && prefix[i-1] == '\t' {
- i--
- }
- prefix = prefix[0:i]
- } else {
- // comment text on the first line
- suffix := make([]byte, len(first))
- n := 2 // start after opening /*
- for n < len(first) && first[n] <= ' ' {
- suffix[n] = first[n]
- n++
- }
- if n > 2 && suffix[2] == '\t' {
- // assume the '\t' compensates for the /*
- suffix = suffix[2:n]
- } else {
- // otherwise assume two blanks
- suffix[0], suffix[1] = ' ', ' '
- suffix = suffix[0:n]
- }
- // Shorten the computed common prefix by the length of
- // suffix, if it is found as suffix of the prefix.
- prefix = strings.TrimSuffix(prefix, string(suffix))
- }
- }
-
- // Handle last line: If it only contains a closing */, align it
- // with the opening /*, otherwise align the text with the other
- // lines.
- last := lines[len(lines)-1]
- closing := "*/"
- i := strings.Index(last, closing) // i >= 0 (closing is always present)
- if isBlank(last[0:i]) {
- // last line only contains closing */
- if lineOfStars {
- closing = " */" // add blank to align final star
- }
- lines[len(lines)-1] = prefix + closing
- } else {
- // last line contains more comment text - assume
- // it is aligned like the other lines and include
- // in prefix computation
- prefix = commonPrefix(prefix, last)
- }
-
- // Remove the common prefix from all but the first and empty lines.
- for i, line := range lines {
- if i > 0 && line != "" {
- lines[i] = line[len(prefix):]
- }
- }
-}
-
-func (p *printer) writeComment(comment *ast.Comment) {
- text := comment.Text
- pos := p.posFor(comment.Pos())
-
- const linePrefix = "//line "
- if strings.HasPrefix(text, linePrefix) && (!pos.IsValid() || pos.Column == 1) {
- // possibly a line directive
- ldir := strings.TrimSpace(text[len(linePrefix):])
- if i := strings.LastIndex(ldir, ":"); i >= 0 {
- if line, err := strconv.Atoi(ldir[i+1:]); err == nil && line > 0 {
- // The line directive we are about to print changed
- // the Filename and Line number used for subsequent
- // tokens. We have to update our AST-space position
- // accordingly and suspend indentation temporarily.
- indent := p.indent
- p.indent = 0
- defer func() {
- p.pos.Filename = ldir[:i]
- p.pos.Line = line
- p.pos.Column = 1
- p.indent = indent
- }()
- }
- }
- }
-
- // shortcut common case of //-style comments
- if text[1] == '/' {
- p.writeString(pos, trimRight(text), true)
- return
- }
-
- // for /*-style comments, print line by line and let the
- // write function take care of the proper indentation
- lines := strings.Split(text, "\n")
-
- // The comment started in the first column but is going
- // to be indented. For an idempotent result, add indentation
- // to all lines such that they look like they were indented
- // before - this will make sure the common prefix computation
- // is the same independent of how many times formatting is
- // applied (was issue 1835).
- if pos.IsValid() && pos.Column == 1 && p.indent > 0 {
- for i, line := range lines[1:] {
- lines[1+i] = " " + line
- }
- }
-
- stripCommonPrefix(lines)
-
- // write comment lines, separated by formfeed,
- // without a line break after the last line
- for i, line := range lines {
- if i > 0 {
- p.writeByte('\f', 1)
- pos = p.pos
- }
- if len(line) > 0 {
- p.writeString(pos, trimRight(line), true)
- }
- }
-}
-
-// writeCommentSuffix writes a line break after a comment if indicated
-// and processes any leftover indentation information. If a line break
-// is needed, the kind of break (newline vs formfeed) depends on the
-// pending whitespace. The writeCommentSuffix result indicates if a
-// newline was written or if a formfeed was dropped from the whitespace
-// buffer.
-//
-func (p *printer) writeCommentSuffix(needsLinebreak bool) (wroteNewline, droppedFF bool) {
- for i, ch := range p.wsbuf {
- switch ch {
- case blank, vtab:
- // ignore trailing whitespace
- p.wsbuf[i] = ignore
- case indent, unindent:
- // don't lose indentation information
- case newline, formfeed:
- // if we need a line break, keep exactly one
- // but remember if we dropped any formfeeds
- if needsLinebreak {
- needsLinebreak = false
- wroteNewline = true
- } else {
- if ch == formfeed {
- droppedFF = true
- }
- p.wsbuf[i] = ignore
- }
- }
- }
- p.writeWhitespace(len(p.wsbuf))
-
- // make sure we have a line break
- if needsLinebreak {
- p.writeByte('\n', 1)
- wroteNewline = true
- }
-
- return
-}
-
-// intersperseComments consumes all comments that appear before the next token
-// tok and prints it together with the buffered whitespace (i.e., the whitespace
-// that needs to be written before the next token). A heuristic is used to mix
-// the comments and whitespace. The intersperseComments result indicates if a
-// newline was written or if a formfeed was dropped from the whitespace buffer.
-//
-func (p *printer) intersperseComments(next token.Position, tok token.Token) (wroteNewline, droppedFF bool) {
- var last *ast.Comment
- for p.commentBefore(next) {
- for _, c := range p.comment.List {
- p.writeCommentPrefix(p.posFor(c.Pos()), next, last, c, tok)
- p.writeComment(c)
- last = c
- }
- p.nextComment()
- }
-
- if last != nil {
- // if the last comment is a /*-style comment and the next item
- // follows on the same line but is not a comma, and not a "closing"
- // token immediately following its corresponding "opening" token,
- // add an extra blank for separation unless explicitly disabled
- if p.mode&noExtraBlank == 0 &&
- last.Text[1] == '*' && p.lineFor(last.Pos()) == next.Line &&
- tok != token.COMMA &&
- (tok != token.RPAREN || p.prevOpen == token.LPAREN) &&
- (tok != token.RBRACK || p.prevOpen == token.LBRACK) {
- p.writeByte(' ', 1)
- }
- // ensure that there is a line break after a //-style comment,
- // before a closing '}' unless explicitly disabled, or at eof
- needsLinebreak :=
- last.Text[1] == '/' ||
- tok == token.RBRACE && p.mode&noExtraLinebreak == 0 ||
- tok == token.EOF
- return p.writeCommentSuffix(needsLinebreak)
- }
-
- // no comment was written - we should never reach here since
- // intersperseComments should not be called in that case
- p.internalError("intersperseComments called without pending comments")
- return
-}
-
-// whiteWhitespace writes the first n whitespace entries.
-func (p *printer) writeWhitespace(n int) {
- // write entries
- for i := 0; i < n; i++ {
- switch ch := p.wsbuf[i]; ch {
- case ignore:
- // ignore!
- case indent:
- p.indent++
- case unindent:
- p.indent--
- if p.indent < 0 {
- p.internalError("negative indentation:", p.indent)
- p.indent = 0
- }
- case newline, formfeed:
- // A line break immediately followed by a "correcting"
- // unindent is swapped with the unindent - this permits
- // proper label positioning. If a comment is between
- // the line break and the label, the unindent is not
- // part of the comment whitespace prefix and the comment
- // will be positioned correctly indented.
- if i+1 < n && p.wsbuf[i+1] == unindent {
- // Use a formfeed to terminate the current section.
- // Otherwise, a long label name on the next line leading
- // to a wide column may increase the indentation column
- // of lines before the label; effectively leading to wrong
- // indentation.
- p.wsbuf[i], p.wsbuf[i+1] = unindent, formfeed
- i-- // do it again
- continue
- }
- fallthrough
- default:
- p.writeByte(byte(ch), 1)
- }
- }
-
- // shift remaining entries down
- l := copy(p.wsbuf, p.wsbuf[n:])
- p.wsbuf = p.wsbuf[:l]
-}
-
-// ----------------------------------------------------------------------------
-// Printing interface
-
-// nlines limits n to maxNewlines.
-func nlimit(n int) int {
- if n > maxNewlines {
- n = maxNewlines
- }
- return n
-}
-
-func mayCombine(prev token.Token, next byte) (b bool) {
- switch prev {
- case token.INT:
- b = next == '.' // 1.
- case token.ADD:
- b = next == '+' // ++
- case token.SUB:
- b = next == '-' // --
- case token.QUO:
- b = next == '*' // /*
- case token.LSS:
- b = next == '-' || next == '<' // <- or <<
- case token.AND:
- b = next == '&' || next == '^' // && or &^
- }
- return
-}
-
-// print prints a list of "items" (roughly corresponding to syntactic
-// tokens, but also including whitespace and formatting information).
-// It is the only print function that should be called directly from
-// any of the AST printing functions in nodes.go.
-//
-// Whitespace is accumulated until a non-whitespace token appears. Any
-// comments that need to appear before that token are printed first,
-// taking into account the amount and structure of any pending white-
-// space for best comment placement. Then, any leftover whitespace is
-// printed, followed by the actual token.
-//
-func (p *printer) print(args ...interface{}) {
- for _, arg := range args {
- // information about the current arg
- var data string
- var isLit bool
- var impliedSemi bool // value for p.impliedSemi after this arg
-
- // record previous opening token, if any
- switch p.lastTok {
- case token.ILLEGAL:
- // ignore (white space)
- case token.LPAREN, token.LBRACK:
- p.prevOpen = p.lastTok
- default:
- // other tokens followed any opening token
- p.prevOpen = token.ILLEGAL
- }
-
- switch x := arg.(type) {
- case pmode:
- // toggle printer mode
- p.mode ^= x
- continue
-
- case whiteSpace:
- if x == ignore {
- // don't add ignore's to the buffer; they
- // may screw up "correcting" unindents (see
- // LabeledStmt)
- continue
- }
- i := len(p.wsbuf)
- if i == cap(p.wsbuf) {
- // Whitespace sequences are very short so this should
- // never happen. Handle gracefully (but possibly with
- // bad comment placement) if it does happen.
- p.writeWhitespace(i)
- i = 0
- }
- p.wsbuf = p.wsbuf[0 : i+1]
- p.wsbuf[i] = x
- if x == newline || x == formfeed {
- // newlines affect the current state (p.impliedSemi)
- // and not the state after printing arg (impliedSemi)
- // because comments can be interspersed before the arg
- // in this case
- p.impliedSemi = false
- }
- p.lastTok = token.ILLEGAL
- continue
-
- case *ast.Ident:
- data = x.Name
- impliedSemi = true
- p.lastTok = token.IDENT
-
- case *ast.BasicLit:
- data = x.Value
- isLit = true
- impliedSemi = true
- p.lastTok = x.Kind
-
- case token.Token:
- s := x.String()
- if mayCombine(p.lastTok, s[0]) {
- // the previous and the current token must be
- // separated by a blank otherwise they combine
- // into a different incorrect token sequence
- // (except for token.INT followed by a '.' this
- // should never happen because it is taken care
- // of via binary expression formatting)
- if len(p.wsbuf) != 0 {
- p.internalError("whitespace buffer not empty")
- }
- p.wsbuf = p.wsbuf[0:1]
- p.wsbuf[0] = ' '
- }
- data = s
- // some keywords followed by a newline imply a semicolon
- switch x {
- case token.BREAK, token.CONTINUE, token.FALLTHROUGH, token.RETURN,
- token.INC, token.DEC, token.RPAREN, token.RBRACK, token.RBRACE:
- impliedSemi = true
- }
- p.lastTok = x
-
- case token.Pos:
- if x.IsValid() {
- p.pos = p.posFor(x) // accurate position of next item
- }
- continue
-
- case string:
- // incorrect AST - print error message
- data = x
- isLit = true
- impliedSemi = true
- p.lastTok = token.STRING
-
- default:
- fmt.Fprintf(os.Stderr, "print: unsupported argument %v (%T)\n", arg, arg)
- panic("go/printer type")
- }
- // data != ""
-
- next := p.pos // estimated/accurate position of next item
- wroteNewline, droppedFF := p.flush(next, p.lastTok)
-
- // intersperse extra newlines if present in the source and
- // if they don't cause extra semicolons (don't do this in
- // flush as it will cause extra newlines at the end of a file)
- if !p.impliedSemi {
- n := nlimit(next.Line - p.pos.Line)
- // don't exceed maxNewlines if we already wrote one
- if wroteNewline && n == maxNewlines {
- n = maxNewlines - 1
- }
- if n > 0 {
- ch := byte('\n')
- if droppedFF {
- ch = '\f' // use formfeed since we dropped one before
- }
- p.writeByte(ch, n)
- impliedSemi = false
- }
- }
-
- // the next token starts now - record its line number if requested
- if p.linePtr != nil {
- *p.linePtr = p.out.Line
- p.linePtr = nil
- }
-
- p.writeString(next, data, isLit)
- p.impliedSemi = impliedSemi
- }
-}
-
-// flush prints any pending comments and whitespace occurring textually
-// before the position of the next token tok. The flush result indicates
-// if a newline was written or if a formfeed was dropped from the whitespace
-// buffer.
-//
-func (p *printer) flush(next token.Position, tok token.Token) (wroteNewline, droppedFF bool) {
- if p.commentBefore(next) {
- // if there are comments before the next item, intersperse them
- wroteNewline, droppedFF = p.intersperseComments(next, tok)
- } else {
- // otherwise, write any leftover whitespace
- p.writeWhitespace(len(p.wsbuf))
- }
- return
-}
-
-// getNode returns the ast.CommentGroup associated with n, if any.
-func getDoc(n ast.Node) *ast.CommentGroup {
- switch n := n.(type) {
- case *ast.Field:
- return n.Doc
- case *ast.ImportSpec:
- return n.Doc
- case *ast.ValueSpec:
- return n.Doc
- case *ast.TypeSpec:
- return n.Doc
- case *ast.GenDecl:
- return n.Doc
- case *ast.FuncDecl:
- return n.Doc
- case *ast.File:
- return n.Doc
- }
- return nil
-}
-
-func (p *printer) printNode(node interface{}) error {
- // unpack *CommentedNode, if any
- var comments []*ast.CommentGroup
- if cnode, ok := node.(*CommentedNode); ok {
- node = cnode.Node
- comments = cnode.Comments
- }
-
- if comments != nil {
- // commented node - restrict comment list to relevant range
- n, ok := node.(ast.Node)
- if !ok {
- goto unsupported
- }
- beg := n.Pos()
- end := n.End()
- // if the node has associated documentation,
- // include that commentgroup in the range
- // (the comment list is sorted in the order
- // of the comment appearance in the source code)
- if doc := getDoc(n); doc != nil {
- beg = doc.Pos()
- }
- // token.Pos values are global offsets, we can
- // compare them directly
- i := 0
- for i < len(comments) && comments[i].End() < beg {
- i++
- }
- j := i
- for j < len(comments) && comments[j].Pos() < end {
- j++
- }
- if i < j {
- p.comments = comments[i:j]
- }
- } else if n, ok := node.(*ast.File); ok {
- // use ast.File comments, if any
- p.comments = n.Comments
- }
-
- // if there are no comments, use node comments
- p.useNodeComments = p.comments == nil
-
- // get comments ready for use
- p.nextComment()
-
- // format node
- switch n := node.(type) {
- case ast.Expr:
- p.expr(n)
- case ast.Stmt:
- // A labeled statement will un-indent to position the label.
- // Set p.indent to 1 so we don't get indent "underflow".
- if _, ok := n.(*ast.LabeledStmt); ok {
- p.indent = 1
- }
- p.stmt(n, false)
- case ast.Decl:
- p.decl(n)
- case ast.Spec:
- p.spec(n, 1, false)
- case []ast.Stmt:
- // A labeled statement will un-indent to position the label.
- // Set p.indent to 1 so we don't get indent "underflow".
- for _, s := range n {
- if _, ok := s.(*ast.LabeledStmt); ok {
- p.indent = 1
- }
- }
- p.stmtList(n, 0, false)
- case []ast.Decl:
- p.declList(n)
- case *ast.File:
- p.file(n)
- default:
- goto unsupported
- }
-
- return nil
-
-unsupported:
- return fmt.Errorf("go/printer: unsupported node type %T", node)
-}
-
-// ----------------------------------------------------------------------------
-// Trimmer
-
-// A trimmer is an io.Writer filter for stripping tabwriter.Escape
-// characters, trailing blanks and tabs, and for converting formfeed
-// and vtab characters into newlines and htabs (in case no tabwriter
-// is used). Text bracketed by tabwriter.Escape characters is passed
-// through unchanged.
-//
-type trimmer struct {
- output io.Writer
- state int
- space []byte
-}
-
-// trimmer is implemented as a state machine.
-// It can be in one of the following states:
-const (
- inSpace = iota // inside space
- inEscape // inside text bracketed by tabwriter.Escapes
- inText // inside text
-)
-
-func (p *trimmer) resetSpace() {
- p.state = inSpace
- p.space = p.space[0:0]
-}
-
-// Design note: It is tempting to eliminate extra blanks occurring in
-// whitespace in this function as it could simplify some
-// of the blanks logic in the node printing functions.
-// However, this would mess up any formatting done by
-// the tabwriter.
-
-var aNewline = []byte("\n")
-
-func (p *trimmer) Write(data []byte) (n int, err error) {
- // invariants:
- // p.state == inSpace:
- // p.space is unwritten
- // p.state == inEscape, inText:
- // data[m:n] is unwritten
- m := 0
- var b byte
- for n, b = range data {
- if b == '\v' {
- b = '\t' // convert to htab
- }
- switch p.state {
- case inSpace:
- switch b {
- case '\t', ' ':
- p.space = append(p.space, b)
- case '\n', '\f':
- p.resetSpace() // discard trailing space
- _, err = p.output.Write(aNewline)
- case tabwriter.Escape:
- _, err = p.output.Write(p.space)
- p.state = inEscape
- m = n + 1 // +1: skip tabwriter.Escape
- default:
- _, err = p.output.Write(p.space)
- p.state = inText
- m = n
- }
- case inEscape:
- if b == tabwriter.Escape {
- _, err = p.output.Write(data[m:n])
- p.resetSpace()
- }
- case inText:
- switch b {
- case '\t', ' ':
- _, err = p.output.Write(data[m:n])
- p.resetSpace()
- p.space = append(p.space, b)
- case '\n', '\f':
- _, err = p.output.Write(data[m:n])
- p.resetSpace()
- _, err = p.output.Write(aNewline)
- case tabwriter.Escape:
- _, err = p.output.Write(data[m:n])
- p.state = inEscape
- m = n + 1 // +1: skip tabwriter.Escape
- }
- default:
- panic("unreachable")
- }
- if err != nil {
- return
- }
- }
- n = len(data)
-
- switch p.state {
- case inEscape, inText:
- _, err = p.output.Write(data[m:n])
- p.resetSpace()
- }
-
- return
-}
-
-// ----------------------------------------------------------------------------
-// Public interface
-
-// A Mode value is a set of flags (or 0). They control printing.
-type Mode uint
-
-const (
- RawFormat Mode = 1 << iota // do not use a tabwriter; if set, UseSpaces is ignored
- TabIndent // use tabs for indentation independent of UseSpaces
- UseSpaces // use spaces instead of tabs for alignment
- SourcePos // emit //line comments to preserve original source positions
-)
-
-// A Config node controls the output of Fprint.
-type Config struct {
- Mode Mode // default: 0
- Tabwidth int // default: 8
- Indent int // default: 0 (all code is indented at least by this much)
-}
-
-// fprint implements Fprint and takes a nodesSizes map for setting up the printer state.
-func (cfg *Config) fprint(output io.Writer, fset *token.FileSet, node interface{}, nodeSizes map[ast.Node]int) (err error) {
- // print node
- var p printer
- p.init(cfg, fset, nodeSizes)
- if err = p.printNode(node); err != nil {
- return
- }
- // print outstanding comments
- p.impliedSemi = false // EOF acts like a newline
- p.flush(token.Position{Offset: infinity, Line: infinity}, token.EOF)
-
- // redirect output through a trimmer to eliminate trailing whitespace
- // (Input to a tabwriter must be untrimmed since trailing tabs provide
- // formatting information. The tabwriter could provide trimming
- // functionality but no tabwriter is used when RawFormat is set.)
- output = &trimmer{output: output}
-
- // redirect output through a tabwriter if necessary
- if cfg.Mode&RawFormat == 0 {
- minwidth := cfg.Tabwidth
-
- padchar := byte('\t')
- if cfg.Mode&UseSpaces != 0 {
- padchar = ' '
- }
-
- twmode := tabwriter.DiscardEmptyColumns
- if cfg.Mode&TabIndent != 0 {
- minwidth = 0
- twmode |= tabwriter.TabIndent
- }
-
- output = tabwriter.NewWriter(output, minwidth, cfg.Tabwidth, 1, padchar, twmode)
- }
-
- // write printer result via tabwriter/trimmer to output
- if _, err = output.Write(p.output); err != nil {
- return
- }
-
- // flush tabwriter, if any
- if tw, _ := output.(*tabwriter.Writer); tw != nil {
- err = tw.Flush()
- }
-
- return
-}
-
-// A CommentedNode bundles an AST node and corresponding comments.
-// It may be provided as argument to any of the Fprint functions.
-//
-type CommentedNode struct {
- Node interface{} // *ast.File, or ast.Expr, ast.Decl, ast.Spec, or ast.Stmt
- Comments []*ast.CommentGroup
-}
-
-// Fprint "pretty-prints" an AST node to output for a given configuration cfg.
-// Position information is interpreted relative to the file set fset.
-// The node type must be *ast.File, *CommentedNode, []ast.Decl, []ast.Stmt,
-// or assignment-compatible to ast.Expr, ast.Decl, ast.Spec, or ast.Stmt.
-//
-func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node interface{}) error {
- return cfg.fprint(output, fset, node, make(map[ast.Node]int))
-}
-
-// Fprint "pretty-prints" an AST node to output.
-// It calls Config.Fprint with default settings.
-//
-func Fprint(output io.Writer, fset *token.FileSet, node interface{}) error {
- return (&Config{Tabwidth: 8}).Fprint(output, fset, node)
-}
generated by cgit v1.2.3 (git 2.39.1) at 2025-04-30 14:11:12 +0000