mirror of
https://github.com/bluekeyes/go-gitdiff
synced 2026-06-08 13:18:30 +00:00
Billy Keyes
1c950ee854
The tests were already split up in this way, so it makes sense to have the parsing functions split as well.
127 lines
3.2 KiB
Go
127 lines
3.2 KiB
Go
// Package gitdiff parses and applies patches generated by Git. It supports
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// line-oriented text patches, binary patches, and can also parse standard
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// unified diffs generated by other tools.
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package gitdiff
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import (
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"bufio"
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"fmt"
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"io"
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)
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// Parse parses a patch with changes to one or more files. Any content before
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// the first file is returned as the second value. If an error occurs while
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// parsing, it returns all files parsed before the error.
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func Parse(r io.Reader) ([]*File, string, error) {
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p := &parser{r: bufio.NewReader(r)}
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if err := p.Next(); err != nil {
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if err == io.EOF {
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return nil, "", nil
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}
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return nil, "", err
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}
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var preamble string
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var files []*File
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for {
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file, pre, err := p.ParseNextFileHeader()
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if err != nil {
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return files, preamble, err
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}
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if file == nil {
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break
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}
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for _, fn := range []func(*File) (int, error){
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p.ParseTextFragments,
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p.ParseBinaryFragments,
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} {
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n, err := fn(file)
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if err != nil {
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return files, preamble, err
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}
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if n > 0 {
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break
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}
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}
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if len(files) == 0 {
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preamble = pre
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}
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files = append(files, file)
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}
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return files, preamble, nil
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}
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// TODO(bkeyes): consider exporting the parser type with configuration
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// this would enable OID validation, p-value guessing, and prefix stripping
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// by allowing users to set or override defaults
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// parser invariants:
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// - methods that parse objects:
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// - start with the parser on the first line of the first object
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// - if returning nil, do not advance
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// - if returning an error, do not advance past the object
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// - if returning an object, advance to the first line after the object
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// - any exported parsing methods must initialize the parser by calling Next()
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type parser struct {
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r *bufio.Reader
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eof bool
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lineno int64
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lines [3]string
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}
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// Next advances the parser by one line. It returns any error encountered while
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// reading the line, including io.EOF when the end of stream is reached.
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func (p *parser) Next() error {
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if p.eof {
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return io.EOF
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}
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if p.lineno == 0 {
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// on first call to next, need to shift in all lines
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for i := 0; i < len(p.lines)-1; i++ {
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if err := p.shiftLines(); err != nil && err != io.EOF {
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return err
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}
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}
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}
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err := p.shiftLines()
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if err != nil && err != io.EOF {
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return err
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}
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p.lineno++
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if p.lines[0] == "" {
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p.eof = true
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return io.EOF
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}
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return nil
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}
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func (p *parser) shiftLines() (err error) {
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for i := 0; i < len(p.lines)-1; i++ {
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p.lines[i] = p.lines[i+1]
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}
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p.lines[len(p.lines)-1], err = p.r.ReadString('\n')
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return
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}
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// Line returns a line from the parser without advancing it. A delta of 0
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// returns the current line, while higher deltas return read-ahead lines. It
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// returns an empty string if the delta is higher than the available lines,
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// either because of the buffer size or because the parser reached the end of
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// the input. Valid lines always contain at least a newline character.
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func (p *parser) Line(delta uint) string {
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return p.lines[delta]
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}
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// Errorf generates an error and appends the current line information.
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func (p *parser) Errorf(delta int64, msg string, args ...interface{}) error {
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return fmt.Errorf("gitdiff: line %d: %s", p.lineno+delta, fmt.Sprintf(msg, args...))
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}
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