| 1 | // Copyright 2013 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package main |
| 6 | |
| 7 | // This file defines utilities for working with file positions. |
| 8 | |
| 9 | import ( |
| 10 | "fmt" |
| 11 | "go/build" |
| 12 | "go/parser" |
| 13 | "go/token" |
| 14 | "os" |
| 15 | "path/filepath" |
| 16 | "strconv" |
| 17 | "strings" |
| 18 | |
| 19 | "golang.org/x/tools/go/ast/astutil" |
| 20 | "golang.org/x/tools/go/buildutil" |
| 21 | ) |
| 22 | |
| 23 | // parseOctothorpDecimal returns the numeric value if s matches "#%d", |
| 24 | // otherwise -1. |
| 25 | func parseOctothorpDecimal(s string) int { |
| 26 | if s != "" && s[0] == '#' { |
| 27 | if s, err := strconv.ParseInt(s[1:], 10, 32); err == nil { |
| 28 | return int(s) |
| 29 | } |
| 30 | } |
| 31 | return -1 |
| 32 | } |
| 33 | |
| 34 | // parsePos parses a string of the form "file:pos" or |
| 35 | // file:start,end" where pos, start, end match #%d and represent byte |
| 36 | // offsets, and returns its components. |
| 37 | // |
| 38 | // (Numbers without a '#' prefix are reserved for future use, |
| 39 | // e.g. to indicate line/column positions.) |
| 40 | func parsePos(pos string) (filename string, startOffset, endOffset int, err error) { |
| 41 | if pos == "" { |
| 42 | err = fmt.Errorf("no source position specified") |
| 43 | return |
| 44 | } |
| 45 | |
| 46 | colon := strings.LastIndex(pos, ":") |
| 47 | if colon < 0 { |
| 48 | err = fmt.Errorf("bad position syntax %q", pos) |
| 49 | return |
| 50 | } |
| 51 | filename, offset := pos[:colon], pos[colon+1:] |
| 52 | startOffset = -1 |
| 53 | endOffset = -1 |
| 54 | if comma := strings.Index(offset, ","); comma < 0 { |
| 55 | // e.g. "foo.go:#123" |
| 56 | startOffset = parseOctothorpDecimal(offset) |
| 57 | endOffset = startOffset |
| 58 | } else { |
| 59 | // e.g. "foo.go:#123,#456" |
| 60 | startOffset = parseOctothorpDecimal(offset[:comma]) |
| 61 | endOffset = parseOctothorpDecimal(offset[comma+1:]) |
| 62 | } |
| 63 | if startOffset < 0 || endOffset < 0 { |
| 64 | err = fmt.Errorf("invalid offset %q in query position", offset) |
| 65 | return |
| 66 | } |
| 67 | return |
| 68 | } |
| 69 | |
| 70 | // fileOffsetToPos translates the specified file-relative byte offsets |
| 71 | // into token.Pos form. It returns an error if the file was not found |
| 72 | // or the offsets were out of bounds. |
| 73 | func fileOffsetToPos(file *token.File, startOffset, endOffset int) (start, end token.Pos, err error) { |
| 74 | // Range check [start..end], inclusive of both end-points. |
| 75 | |
| 76 | if 0 <= startOffset && startOffset <= file.Size() { |
| 77 | start = file.Pos(int(startOffset)) |
| 78 | } else { |
| 79 | err = fmt.Errorf("start position is beyond end of file") |
| 80 | return |
| 81 | } |
| 82 | |
| 83 | if 0 <= endOffset && endOffset <= file.Size() { |
| 84 | end = file.Pos(int(endOffset)) |
| 85 | } else { |
| 86 | err = fmt.Errorf("end position is beyond end of file") |
| 87 | return |
| 88 | } |
| 89 | |
| 90 | return |
| 91 | } |
| 92 | |
| 93 | // sameFile returns true if x and y have the same basename and denote |
| 94 | // the same file. |
| 95 | func sameFile(x, y string) bool { |
| 96 | if filepath.Base(x) == filepath.Base(y) { // (optimisation) |
| 97 | if xi, err := os.Stat(x); err == nil { |
| 98 | if yi, err := os.Stat(y); err == nil { |
| 99 | return os.SameFile(xi, yi) |
| 100 | } |
| 101 | } |
| 102 | } |
| 103 | return false |
| 104 | } |
| 105 | |
| 106 | // fastQueryPos parses the position string and returns a queryPos. |
| 107 | // It parses only a single file and does not run the type checker. |
| 108 | func fastQueryPos(ctxt *build.Context, pos string) (*queryPos, error) { |
| 109 | filename, startOffset, endOffset, err := parsePos(pos) |
| 110 | if err != nil { |
| 111 | return nil, err |
| 112 | } |
| 113 | |
| 114 | // Parse the file, opening it the file via the build.Context |
| 115 | // so that we observe the effects of the -modified flag. |
| 116 | fset := token.NewFileSet() |
| 117 | cwd, _ := os.Getwd() |
| 118 | f, err := buildutil.ParseFile(fset, ctxt, nil, cwd, filename, parser.Mode(0)) |
| 119 | // ParseFile usually returns a partial file along with an error. |
| 120 | // Only fail if there is no file. |
| 121 | if f == nil { |
| 122 | return nil, err |
| 123 | } |
| 124 | if !f.Pos().IsValid() { |
| 125 | return nil, fmt.Errorf("%s is not a Go source file", filename) |
| 126 | } |
| 127 | |
| 128 | start, end, err := fileOffsetToPos(fset.File(f.Pos()), startOffset, endOffset) |
| 129 | if err != nil { |
| 130 | return nil, err |
| 131 | } |
| 132 | |
| 133 | path, exact := astutil.PathEnclosingInterval(f, start, end) |
| 134 | if path == nil { |
| 135 | return nil, fmt.Errorf("no syntax here") |
| 136 | } |
| 137 | |
| 138 | return &queryPos{fset, start, end, path, exact, nil}, nil |
| 139 | } |
| 140 |
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