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Document and enforce parser invariants
After considering fragment parsing, it made sense to change the
invariant estabilished in the previous commit. Specifically, parser
functions now assume they are call on the first line of their object and
return with the parser on the first line after their object. This means
code can call parse function immediately after each other without
advancing the parser in between.
It's possible this will change back later on... there seem to be
annoying edge cases with either choice, but I think making the functions
consistent is important.
+110
-78
+8
-4
gitdiff/file_header.go
+8
-4
gitdiff/file_header.go
···
32
32
if err != nil {
33
33
return nil, p.Errorf(1, "git file header: %v", err)
34
34
}
35
-
if end {
36
-
break
37
-
}
38
35
39
36
if err := p.Next(); err != nil {
40
37
if err == io.EOF {
41
38
break
42
39
}
43
40
return nil, err
41
+
}
42
+
43
+
if end {
44
+
break
44
45
}
45
46
}
46
47
···
76
77
return nil, nil
77
78
}
78
79
79
-
// advance past the first line so parser is at end of header
80
+
// advance past the first two lines so parser is after the header
80
81
// no EOF check needed because we know there are >=3 valid lines
82
+
if err := p.Next(); err != nil {
83
+
return nil, err
84
+
}
81
85
if err := p.Next(); err != nil {
82
86
return nil, err
83
87
}
-54
gitdiff/file_header_test.go
-54
gitdiff/file_header_test.go
···
277
277
}
278
278
}
279
279
280
-
func TestParserAdvancment(t *testing.T) {
281
-
tests := map[string]struct {
282
-
Input string
283
-
Parse func(p *parser) error
284
-
NextLine string
285
-
}{
286
-
"ParseGitFileHeader": {
287
-
Input: `diff --git a/dir/file.txt b/dir/file.txt
288
-
index 9540595..30e6333 100644
289
-
--- a/dir/file.txt
290
-
+++ b/dir/file.txt
291
-
@@ -1,2 +1,3 @@
292
-
context line
293
-
`,
294
-
Parse: func(p *parser) error {
295
-
_, err := p.ParseGitFileHeader()
296
-
return err
297
-
},
298
-
NextLine: "@@ -1,2 +1,3 @@\n",
299
-
},
300
-
"ParseTraditionalFileHeader": {
301
-
Input: `--- dir/file.txt
302
-
+++ dir/file.txt
303
-
@@ -1,2 +1,3 @@
304
-
context line
305
-
`,
306
-
Parse: func(p *parser) error {
307
-
_, err := p.ParseTraditionalFileHeader()
308
-
return err
309
-
},
310
-
NextLine: "@@ -1,2 +1,3 @@\n",
311
-
},
312
-
}
313
-
314
-
for name, test := range tests {
315
-
t.Run(name, func(t *testing.T) {
316
-
p := &parser{r: bufio.NewReader(strings.NewReader(test.Input))}
317
-
p.Next()
318
-
319
-
if err := test.Parse(p); err != nil {
320
-
t.Fatalf("unexpected error while parsing: %v", err)
321
-
}
322
-
323
-
if err := p.Next(); err != nil {
324
-
t.Fatalf("advancing the parser after parsing returned an error: %v", err)
325
-
}
326
-
327
-
if test.NextLine != p.Line(0) {
328
-
t.Errorf("incorrect next line after parsing\nexpected: %q\nactual: %q", test.NextLine, p.Line(0))
329
-
}
330
-
})
331
-
}
332
-
}
333
-
334
280
func TestCleanName(t *testing.T) {
335
281
tests := map[string]struct {
336
282
Input string
+6
gitdiff/gitdiff.go
+6
gitdiff/gitdiff.go
···
1
1
package gitdiff
2
2
3
3
import (
4
+
"fmt"
4
5
"os"
5
6
)
6
7
···
35
36
NewPosition int64
36
37
NewLines int64
37
38
}
39
+
40
+
// Header returns the cannonical header of this fragment.
41
+
func (f *Fragment) Header() string {
42
+
return fmt.Sprintf("@@ -%d,%d +%d,%d @@ %s", f.OldPosition, f.OldLines, f.NewPosition, f.NewLines, f.Comment)
43
+
}
+36
-20
gitdiff/parser.go
+36
-20
gitdiff/parser.go
···
11
11
// Parse parses a patch with changes for one or more files. Any content
12
12
// preceding the first file header is ignored. If an error occurs while
13
13
// parsing, files will contain all files parsed before the error.
14
-
func Parse(r io.Reader) (files []*File, err error) {
14
+
func Parse(r io.Reader) ([]*File, error) {
15
15
p := &parser{r: bufio.NewReader(r)}
16
+
if err := p.Next(); err != nil {
17
+
if err == io.EOF {
18
+
return nil, nil
19
+
}
20
+
return nil, err
21
+
}
16
22
17
-
var file *File
23
+
var files []*File
18
24
for {
19
-
file, err = p.ParseNextFileHeader()
25
+
file, err := p.ParseNextFileHeader()
20
26
if err != nil {
21
-
return
27
+
return files, err
22
28
}
23
29
if file == nil {
24
30
break
25
31
}
26
32
27
-
err = p.ParseFileChanges(file)
28
-
if err != nil {
29
-
return
33
+
if err = p.ParseFragments(file); err != nil {
34
+
return files, err
30
35
}
31
36
32
37
files = append(files, file)
···
39
44
// this would enable OID validation, p-value guessing, and prefix stripping
40
45
// by allowing users to set or override defaults
41
46
47
+
// parser invariants:
48
+
// - methods that parse objects start on the first line of the first object
49
+
// - methods that parse objects return on the first line after the last object
50
+
// - if a parse method returns a nil object, the parser was not advanced
51
+
// - any exported parsing methods must initialize the parser by calling Next()
52
+
42
53
type parser struct {
43
54
r *bufio.Reader
44
55
···
50
61
// ParseNextFileHeader finds and parses the next file header in the stream. It
51
62
// returns nil if no headers are found before the end of the stream.
52
63
func (p *parser) ParseNextFileHeader() (*File, error) {
64
+
var file *File
53
65
for {
54
-
if err := p.Next(); err != nil {
55
-
if err == io.EOF {
56
-
break
57
-
}
58
-
return nil, err
59
-
}
60
-
61
66
// check for disconnected fragment headers (corrupt patch)
62
67
frag, err := p.ParseFragmentHeader()
63
68
if err != nil {
64
69
// not a valid header, nothing to worry about
65
-
continue
70
+
goto NextLine
66
71
}
67
72
if frag != nil {
68
-
return nil, p.Errorf(0, "patch fragment without header: %s", p.Line(0))
73
+
return nil, p.Errorf(-1, "patch fragment without file header: %s", frag.Header())
69
74
}
70
75
71
76
// check for a git-generated patch
72
-
file, err := p.ParseGitFileHeader()
77
+
file, err = p.ParseGitFileHeader()
73
78
if err != nil {
74
79
return nil, err
75
80
}
···
85
90
if file != nil {
86
91
return file, nil
87
92
}
93
+
94
+
NextLine:
95
+
if err := p.Next(); err != nil {
96
+
if err == io.EOF {
97
+
break
98
+
}
99
+
return nil, err
100
+
}
88
101
}
89
102
return nil, nil
90
103
}
91
104
92
-
// ParseFileChanges parses file changes until the next file header or the end
93
-
// of the stream and attaches them to the given file.
94
-
func (p *parser) ParseFileChanges(f *File) error {
105
+
// ParseFragments parses fragments until the next file header or the end of the
106
+
// stream and attaches them to the given file.
107
+
func (p *parser) ParseFragments(f *File) error {
95
108
panic("TODO(bkeyes): unimplemented")
96
109
}
97
110
···
177
190
return nil, fmt.Errorf("invalid fragment header: %v", err)
178
191
}
179
192
193
+
if err := p.Next(); err != nil && err != io.EOF {
194
+
return nil, err
195
+
}
180
196
return f, nil
181
197
}
182
198
+60
gitdiff/parser_test.go
+60
gitdiff/parser_test.go
···
73
73
})
74
74
}
75
75
76
+
func TestParserAdvancment(t *testing.T) {
77
+
tests := map[string]struct {
78
+
Input string
79
+
Parse func(p *parser) error
80
+
EndLine string
81
+
}{
82
+
"ParseGitFileHeader": {
83
+
Input: `diff --git a/dir/file.txt b/dir/file.txt
84
+
index 9540595..30e6333 100644
85
+
--- a/dir/file.txt
86
+
+++ b/dir/file.txt
87
+
@@ -1,2 +1,3 @@
88
+
context line
89
+
`,
90
+
Parse: func(p *parser) error {
91
+
_, err := p.ParseGitFileHeader()
92
+
return err
93
+
},
94
+
EndLine: "@@ -1,2 +1,3 @@\n",
95
+
},
96
+
"ParseTraditionalFileHeader": {
97
+
Input: `--- dir/file.txt
98
+
+++ dir/file.txt
99
+
@@ -1,2 +1,3 @@
100
+
context line
101
+
`,
102
+
Parse: func(p *parser) error {
103
+
_, err := p.ParseTraditionalFileHeader()
104
+
return err
105
+
},
106
+
EndLine: "@@ -1,2 +1,3 @@\n",
107
+
},
108
+
"ParseFragmentHeader": {
109
+
Input: `@@ -1,2 +1,3 @@
110
+
context line
111
+
`,
112
+
Parse: func(p *parser) error {
113
+
_, err := p.ParseFragmentHeader()
114
+
return err
115
+
},
116
+
EndLine: "context line\n",
117
+
},
118
+
}
119
+
120
+
for name, test := range tests {
121
+
t.Run(name, func(t *testing.T) {
122
+
p := &parser{r: bufio.NewReader(strings.NewReader(test.Input))}
123
+
p.Next()
124
+
125
+
if err := test.Parse(p); err != nil {
126
+
t.Fatalf("unexpected error while parsing: %v", err)
127
+
}
128
+
129
+
if test.EndLine != p.Line(0) {
130
+
t.Errorf("incorrect position after parsing\nexpected: %q\nactual: %q", test.EndLine, p.Line(0))
131
+
}
132
+
})
133
+
}
134
+
}
135
+
76
136
func TestParseFragmentHeader(t *testing.T) {
77
137
tests := map[string]struct {
78
138
Input string