summaryrefslogtreecommitdiff
path: root/src/pkg/go/parser/interface.go
blob: 57da4ddcd9302352c168c005799cb75e4f75a677 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
// 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.

// This file contains the exported entry points for invoking the parser.

package parser

import (
	"bytes"
	"errors"
	"go/ast"
	"go/token"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
)

// If src != nil, readSource converts src to a []byte if possible;
// otherwise it returns an error. If src == nil, readSource returns
// the result of reading the file specified by filename.
//
func readSource(filename string, src interface{}) ([]byte, error) {
	if src != nil {
		switch s := src.(type) {
		case string:
			return []byte(s), nil
		case []byte:
			return s, nil
		case *bytes.Buffer:
			// is io.Reader, but src is already available in []byte form
			if s != nil {
				return s.Bytes(), nil
			}
		case io.Reader:
			var buf bytes.Buffer
			if _, err := io.Copy(&buf, s); err != nil {
				return nil, err
			}
			return buf.Bytes(), nil
		}
		return nil, errors.New("invalid source")
	}
	return ioutil.ReadFile(filename)
}

// A Mode value is a set of flags (or 0).
// They control the amount of source code parsed and other optional
// parser functionality.
//
type Mode uint

const (
	PackageClauseOnly Mode             = 1 << iota // stop parsing after package clause
	ImportsOnly                                    // stop parsing after import declarations
	ParseComments                                  // parse comments and add them to AST
	Trace                                          // print a trace of parsed productions
	DeclarationErrors                              // report declaration errors
	SpuriousErrors                                 // same as AllErrors, for backward-compatibility
	AllErrors         = SpuriousErrors             // report all errors (not just the first 10 on different lines)
)

// ParseFile parses the source code of a single Go source file and returns
// the corresponding ast.File node. The source code may be provided via
// the filename of the source file, or via the src parameter.
//
// If src != nil, ParseFile parses the source from src and the filename is
// only used when recording position information. The type of the argument
// for the src parameter must be string, []byte, or io.Reader.
// If src == nil, ParseFile parses the file specified by filename.
//
// The mode parameter controls the amount of source text parsed and other
// optional parser functionality. Position information is recorded in the
// file set fset.
//
// If the source couldn't be read, the returned AST is nil and the error
// indicates the specific failure. If the source was read but syntax
// errors were found, the result is a partial AST (with ast.Bad* nodes
// representing the fragments of erroneous source code). Multiple errors
// are returned via a scanner.ErrorList which is sorted by file position.
//
func ParseFile(fset *token.FileSet, filename string, src interface{}, mode Mode) (f *ast.File, err error) {
	// get source
	text, err := readSource(filename, src)
	if err != nil {
		return nil, err
	}

	var p parser
	defer func() {
		if e := recover(); e != nil {
			_ = e.(bailout) // re-panics if it's not a bailout
		}

		// set result values
		if f == nil {
			// source is not a valid Go source file - satisfy
			// ParseFile API and return a valid (but) empty
			// *ast.File
			f = &ast.File{
				Name:  new(ast.Ident),
				Scope: ast.NewScope(nil),
			}
		}

		p.errors.Sort()
		err = p.errors.Err()
	}()

	// parse source
	p.init(fset, filename, text, mode)
	f = p.parseFile()

	return
}

// ParseDir calls ParseFile for all files with names ending in ".go" in the
// directory specified by path and returns a map of package name -> package
// AST with all the packages found.
//
// If filter != nil, only the files with os.FileInfo entries passing through
// the filter (and ending in ".go") are considered. The mode bits are passed
// to ParseFile unchanged. Position information is recorded in fset.
//
// If the directory couldn't be read, a nil map and the respective error are
// returned. If a parse error occurred, a non-nil but incomplete map and the
// first error encountered are returned.
//
func ParseDir(fset *token.FileSet, path string, filter func(os.FileInfo) bool, mode Mode) (pkgs map[string]*ast.Package, first error) {
	fd, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer fd.Close()

	list, err := fd.Readdir(-1)
	if err != nil {
		return nil, err
	}

	pkgs = make(map[string]*ast.Package)
	for _, d := range list {
		if strings.HasSuffix(d.Name(), ".go") && (filter == nil || filter(d)) {
			filename := filepath.Join(path, d.Name())
			if src, err := ParseFile(fset, filename, nil, mode); err == nil {
				name := src.Name.Name
				pkg, found := pkgs[name]
				if !found {
					pkg = &ast.Package{
						Name:  name,
						Files: make(map[string]*ast.File),
					}
					pkgs[name] = pkg
				}
				pkg.Files[filename] = src
			} else if first == nil {
				first = err
			}
		}
	}

	return
}

// ParseExpr is a convenience function for obtaining the AST of an expression x.
// The position information recorded in the AST is undefined. The filename used
// in error messages is the empty string.
//
func ParseExpr(x string) (ast.Expr, error) {
	var p parser
	p.init(token.NewFileSet(), "", []byte(x), 0)

	// Set up pkg-level scopes to avoid nil-pointer errors.
	// This is not needed for a correct expression x as the
	// parser will be ok with a nil topScope, but be cautious
	// in case of an erroneous x.
	p.openScope()
	p.pkgScope = p.topScope
	e := p.parseRhsOrType()
	p.closeScope()
	assert(p.topScope == nil, "unbalanced scopes")

	// If a semicolon was inserted, consume it;
	// report an error if there's more tokens.
	if p.tok == token.SEMICOLON {
		p.next()
	}
	p.expect(token.EOF)

	if p.errors.Len() > 0 {
		p.errors.Sort()
		return nil, p.errors.Err()
	}

	return e, nil
}