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
5package loader
6
7import (
8 "go/ast"
9 "go/build"
10 "go/parser"
11 "go/token"
12 "io"
13 "os"
14 "strconv"
15 "sync"
16
17 "golang.org/x/tools/go/buildutil"
18)
19
20// We use a counting semaphore to limit
21// the number of parallel I/O calls per process.
22var ioLimit = make(chan bool, 10)
23
24// parseFiles parses the Go source files within directory dir and
25// returns the ASTs of the ones that could be at least partially parsed,
26// along with a list of I/O and parse errors encountered.
27//
28// I/O is done via ctxt, which may specify a virtual file system.
29// displayPath is used to transform the filenames attached to the ASTs.
30//
31func parseFiles(fset *token.FileSet, ctxt *build.Context, displayPath func(string) string, dir string, files []string, mode parser.Mode) ([]*ast.File, []error) {
32 if displayPath == nil {
33 displayPath = func(path string) string { return path }
34 }
35 var wg sync.WaitGroup
36 n := len(files)
37 parsed := make([]*ast.File, n)
38 errors := make([]error, n)
39 for i, file := range files {
40 if !buildutil.IsAbsPath(ctxt, file) {
41 file = buildutil.JoinPath(ctxt, dir, file)
42 }
43 wg.Add(1)
44 go func(i int, file string) {
45 ioLimit <- true // wait
46 defer func() {
47 wg.Done()
48 <-ioLimit // signal
49 }()
50 var rd io.ReadCloser
51 var err error
52 if ctxt.OpenFile != nil {
53 rd, err = ctxt.OpenFile(file)
54 } else {
55 rd, err = os.Open(file)
56 }
57 if err != nil {
58 errors[i] = err // open failed
59 return
60 }
61
62 // ParseFile may return both an AST and an error.
63 parsed[i], errors[i] = parser.ParseFile(fset, displayPath(file), rd, mode)
64 rd.Close()
65 }(i, file)
66 }
67 wg.Wait()
68
69 // Eliminate nils, preserving order.
70 var o int
71 for _, f := range parsed {
72 if f != nil {
73 parsed[o] = f
74 o++
75 }
76 }
77 parsed = parsed[:o]
78
79 o = 0
80 for _, err := range errors {
81 if err != nil {
82 errors[o] = err
83 o++
84 }
85 }
86 errors = errors[:o]
87
88 return parsed, errors
89}
90
91// scanImports returns the set of all import paths from all
92// import specs in the specified files.
93func scanImports(files []*ast.File) map[string]bool {
94 imports := make(map[string]bool)
95 for _, f := range files {
96 for _, decl := range f.Decls {
97 if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.IMPORT {
98 for _, spec := range decl.Specs {
99 spec := spec.(*ast.ImportSpec)
100
101 // NB: do not assume the program is well-formed!
102 path, err := strconv.Unquote(spec.Path.Value)
103 if err != nil {
104 continue // quietly ignore the error
105 }
106 if path == "C" {
107 continue // skip pseudopackage
108 }
109 imports[path] = true
110 }
111 }
112 }
113 }
114 return imports
115}
116
117// ---------- Internal helpers ----------
118
119// TODO(adonovan): make this a method: func (*token.File) Contains(token.Pos)
120func tokenFileContainsPos(f *token.File, pos token.Pos) bool {
121 p := int(pos)
122 base := f.Base()
123 return base <= p && p < base+f.Size()
124}