diff options
Diffstat (limited to 'libgo/go/golang.org/x/mod/modfile/print.go')
-rw-r--r-- | libgo/go/golang.org/x/mod/modfile/print.go | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/libgo/go/golang.org/x/mod/modfile/print.go b/libgo/go/golang.org/x/mod/modfile/print.go new file mode 100644 index 00000000000..3bbea38529f --- /dev/null +++ b/libgo/go/golang.org/x/mod/modfile/print.go @@ -0,0 +1,165 @@ +// Copyright 2018 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. + +// Module file printer. + +package modfile + +import ( + "bytes" + "fmt" + "strings" +) + +// Format returns a go.mod file as a byte slice, formatted in standard style. +func Format(f *FileSyntax) []byte { + pr := &printer{} + pr.file(f) + return pr.Bytes() +} + +// A printer collects the state during printing of a file or expression. +type printer struct { + bytes.Buffer // output buffer + comment []Comment // pending end-of-line comments + margin int // left margin (indent), a number of tabs +} + +// printf prints to the buffer. +func (p *printer) printf(format string, args ...interface{}) { + fmt.Fprintf(p, format, args...) +} + +// indent returns the position on the current line, in bytes, 0-indexed. +func (p *printer) indent() int { + b := p.Bytes() + n := 0 + for n < len(b) && b[len(b)-1-n] != '\n' { + n++ + } + return n +} + +// newline ends the current line, flushing end-of-line comments. +func (p *printer) newline() { + if len(p.comment) > 0 { + p.printf(" ") + for i, com := range p.comment { + if i > 0 { + p.trim() + p.printf("\n") + for i := 0; i < p.margin; i++ { + p.printf("\t") + } + } + p.printf("%s", strings.TrimSpace(com.Token)) + } + p.comment = p.comment[:0] + } + + p.trim() + p.printf("\n") + for i := 0; i < p.margin; i++ { + p.printf("\t") + } +} + +// trim removes trailing spaces and tabs from the current line. +func (p *printer) trim() { + // Remove trailing spaces and tabs from line we're about to end. + b := p.Bytes() + n := len(b) + for n > 0 && (b[n-1] == '\t' || b[n-1] == ' ') { + n-- + } + p.Truncate(n) +} + +// file formats the given file into the print buffer. +func (p *printer) file(f *FileSyntax) { + for _, com := range f.Before { + p.printf("%s", strings.TrimSpace(com.Token)) + p.newline() + } + + for i, stmt := range f.Stmt { + switch x := stmt.(type) { + case *CommentBlock: + // comments already handled + p.expr(x) + + default: + p.expr(x) + p.newline() + } + + for _, com := range stmt.Comment().After { + p.printf("%s", strings.TrimSpace(com.Token)) + p.newline() + } + + if i+1 < len(f.Stmt) { + p.newline() + } + } +} + +func (p *printer) expr(x Expr) { + // Emit line-comments preceding this expression. + if before := x.Comment().Before; len(before) > 0 { + // Want to print a line comment. + // Line comments must be at the current margin. + p.trim() + if p.indent() > 0 { + // There's other text on the line. Start a new line. + p.printf("\n") + } + // Re-indent to margin. + for i := 0; i < p.margin; i++ { + p.printf("\t") + } + for _, com := range before { + p.printf("%s", strings.TrimSpace(com.Token)) + p.newline() + } + } + + switch x := x.(type) { + default: + panic(fmt.Errorf("printer: unexpected type %T", x)) + + case *CommentBlock: + // done + + case *LParen: + p.printf("(") + case *RParen: + p.printf(")") + + case *Line: + sep := "" + for _, tok := range x.Token { + p.printf("%s%s", sep, tok) + sep = " " + } + + case *LineBlock: + for _, tok := range x.Token { + p.printf("%s ", tok) + } + p.expr(&x.LParen) + p.margin++ + for _, l := range x.Line { + p.newline() + p.expr(l) + } + p.margin-- + p.newline() + p.expr(&x.RParen) + } + + // Queue end-of-line comments for printing when we + // reach the end of the line. + p.comment = append(p.comment, x.Comment().Suffix...) +} |