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| 1 | | // Package generated provides a function that parses a Go file and reports
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| 1 | // Package generated provides a function that parses a source file and reports
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| 2 | 2 | // whether it contains a "// Code generated … DO NOT EDIT." line comment.
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| 3 | 3 | //
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| 4 | | // It implements the specification at https://golang.org/s/generatedcode.
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| 4 | // It implements the specification at https://go.dev/s/generatedcode.
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| 5 | 5 | //
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| 6 | 6 | // The first priority is correctness (no false negatives, no false positives).
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| 7 | | // It must return accurate results even if the input Go source code is not gofmted.
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| 7 | // It must return accurate results even if the input source code is formatted
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| 8 | // unconventionally.
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| 8 | 9 | //
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| 9 | 10 | // The second priority is performance. The current version uses bufio.Reader and
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| 10 | 11 | // ReadBytes. Performance can be optimized further by using lower level I/O
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| 11 | | // primitives and allocating less. That can be explored later. A lot of the time
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| 12 | | // is spent on reading the entire file without being able to stop early,
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| 13 | | // since the specification allows the comment to appear anywhere in the file.
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| 12 | // primitives and allocating less. That can be explored later.
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| 14 | 13 | package generated
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| 15 | 14 |
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| 16 | 15 | import (
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| 17 | 16 | "bufio"
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| 18 | 17 | "bytes"
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| 19 | 18 | "io"
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| 20 | 19 | "os"
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| 21 | 20 | )
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| 22 | 21 |
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| 23 | | // Parse parses the source code of a single Go source file
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| 24 | | // provided via src, and reports whether the file contains
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| 25 | | // a "// Code generated ... DO NOT EDIT." line comment
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| 26 | | // matching the specification at https://golang.org/s/generatedcode:
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| 22 | // Parse parses a source file provided via src, and reports whether
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| 23 | // the file contains a "// Code generated ... DO NOT EDIT." line comment
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| 24 | // matching the specification at https://go.dev/s/generatedcode:
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| 27 | 25 | //
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| 28 | | // Generated files are marked by a line of text that matches
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| 29 | | // the regular expression, in Go syntax:
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| 26 | // To convey to humans and machine tools that code is generated,
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| 27 | // generated source should have a line that matches the following
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| 28 | // regular expression (in Go syntax):
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| 30 | 29 | //
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| 31 | 30 | // ^// Code generated .* DO NOT EDIT\.$
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| 32 | 31 | //
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| 33 | | // The .* means the tool can put whatever folderol it wants in there,
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| 34 | | // but the comment must be a single line and must start with Code generated
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| 35 | | // and end with DO NOT EDIT., with a period.
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| 36 | | //
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| 37 | | // The text may appear anywhere in the file.
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| 32 | // This line must appear before the first non-comment, non-blank
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| 33 | // text in the file.
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| 38 | 34 | func Parse(src io.Reader) (hasGeneratedComment bool, err error) {
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| 39 | 35 | br := bufio.NewReader(src)
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| 36 | // Use inBlock to track whether we're inside a multi-line
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| 37 | // /* */ comment block across calls to containsNonComment.
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| 38 | var inBlock bool
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| 40 | 39 | for {
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| 41 | 40 | s, err := br.ReadBytes('\n')
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| 42 | 41 | if err == io.EOF {
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| 43 | | return containsComment(s), nil
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| 42 | return containsGenComment(s), nil
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| 44 | 43 | } else if err != nil {
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| 45 | 44 | return false, err
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| 46 | 45 | }
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| 47 | 46 | if len(s) >= 2 && s[len(s)-2] == '\r' {
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| 48 | 47 | s = s[:len(s)-2] // Trim "\r\n".
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| 49 | 48 | } else {
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| 50 | 49 | s = s[:len(s)-1] // Trim "\n".
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| 51 | 50 | }
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| 52 | | if containsComment(s) {
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| 51 | if containsGenComment(s) {
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| 53 | 52 | return true, nil
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| 53 | } else if containsNonComment(s, &inBlock) {
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| 54 | return false, nil
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| 54 | 55 | }
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| 55 | 56 | }
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| 56 | 57 | }
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| 57 | 58 |
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| 58 | | // containsComment reports whether a line of Go source code s (without newline character)
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| 59 | // containsNonComment reports whether a line of source code s (without newline)
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| 60 | // contains something other than a line comment, block comment, or white space.
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| 61 | func containsNonComment(s []byte, inBlock *bool) bool {
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| 62 | type state int
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| 63 | const (
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| 64 | normal state = iota
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| 65 | normalSlash
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| 66 | block
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| 67 | blockStar
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| 68 | )
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| 69 | var p state // Parser state.
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| 70 | if *inBlock {
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| 71 | p = block
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| 72 | }
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| 73 | for _, c := range s {
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| 74 | switch p {
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| 75 | case normal:
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| 76 | switch c {
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| 77 | case ' ', '\t': // White space, ignore.
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| 78 | case '/':
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| 79 | p = normalSlash
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| 80 | default: // Non-comment found.
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| 81 | return true // Return early and don't bother updating *inBlock since it won't matter.
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| 82 | }
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| 83 | case normalSlash:
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| 84 | switch c {
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| 85 | case '/': // Start of inline comment, "//". Ignore the rest of the line.
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| 86 | *inBlock = false
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| 87 | return false
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| 88 | case '*': // Start of comment block, "/*".
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| 89 | p = block
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| 90 | default: // Non-comment found.
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| 91 | return true // Return early and don't bother updating *inBlock since it won't matter.
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| 92 | }
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| 93 | case block:
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| 94 | switch c {
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| 95 | case '*':
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| 96 | p = blockStar
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| 97 | }
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| 98 | case blockStar:
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| 99 | switch c {
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| 100 | case '/': // End of comment block, "*/".
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| 101 | p = normal
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| 102 | case '*': // Another '*', stay in blockStar.
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| 103 | default:
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| 104 | p = block
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| 105 | }
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| 106 | }
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| 107 | }
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| 108 | *inBlock = p >= block
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| 109 | return p == normalSlash
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| 110 | }
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| 111 |
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| 112 | // containsGenComment reports whether a line of source code s (without newline)
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| 59 | 113 | // contains the generated comment.
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| 60 | | func containsComment(s []byte) bool {
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| 114 | func containsGenComment(s []byte) bool {
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| 61 | 115 | return len(s) >= len(prefix)+len(suffix) &&
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| 62 | 116 | bytes.HasPrefix(s, prefix) &&
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| 63 | 117 | bytes.HasSuffix(s, suffix)
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| 64 | 118 | }
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| 65 | 119 |
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