// Package revision extracts git revision from string
// More informations about revision : https://www.kernel.org/pub/software/scm/git/docs/gitrevisions.html
package revision
import (
"bytes"
"fmt"
"io"
"regexp"
"strconv"
"time"
)
// ErrInvalidRevision is emitted if string doesn't match valid revision
type ErrInvalidRevision struct {
s string
}
func (e *ErrInvalidRevision) Error() string {
return "Revision invalid : " + e.s
}
// Revisioner represents a revision component.
// A revision is made of multiple revision components
// obtained after parsing a revision string,
// for instance revision "master~" will be converted in
// two revision components Ref and TildePath
type Revisioner interface {
}
// Ref represents a reference name : HEAD, master
type Ref string
// TildePath represents ~, ~{n}
type TildePath struct {
Depth int
}
// CaretPath represents ^, ^{n}
type CaretPath struct {
Depth int
}
// CaretReg represents ^{/foo bar}
type CaretReg struct {
Regexp *regexp.Regexp
Negate bool
}
// CaretType represents ^{commit}
type CaretType struct {
ObjectType string
}
// AtReflog represents @{n}
type AtReflog struct {
Depth int
}
// AtCheckout represents @{-n}
type AtCheckout struct {
Depth int
}
// AtUpstream represents @{upstream}, @{u}
type AtUpstream struct {
BranchName string
}
// AtPush represents @{push}
type AtPush struct {
BranchName string
}
// AtDate represents @{"2006-01-02T15:04:05Z"}
type AtDate struct {
Date time.Time
}
// ColonReg represents :/foo bar
type ColonReg struct {
Regexp *regexp.Regexp
Negate bool
}
// ColonPath represents :./<path> :<path>
type ColonPath struct {
Path string
}
// ColonStagePath represents :<n>:/<path>
type ColonStagePath struct {
Path string
Stage int
}
// Parser represents a parser
// use to tokenize and transform to revisioner chunks
// a given string
type Parser struct {
s *scanner
currentParsedChar struct {
tok token
lit string
}
unreadLastChar bool
}
// NewParserFromString returns a new instance of parser from a string.
func NewParserFromString(s string) *Parser {
return NewParser(bytes.NewBufferString(s))
}
// NewParser returns a new instance of parser.
func NewParser(r io.Reader) *Parser {
return &Parser{s: newScanner(r)}
}
// scan returns the next token from the underlying scanner
// or the last scanned token if an unscan was requested
func (p *Parser) scan() (token, string, error) {
if p.unreadLastChar {
p.unreadLastChar = false
return p.currentParsedChar.tok, p.currentParsedChar.lit, nil
}
tok, lit, err := p.s.scan()
p.currentParsedChar.tok, p.currentParsedChar.lit = tok, lit
return tok, lit, err
}
// unscan pushes the previously read token back onto the buffer.
func (p *Parser) unscan() { p.unreadLastChar = true }
// Parse explode a revision string into revisioner chunks
func (p *Parser) Parse() ([]Revisioner, error) {
var rev Revisioner
var revs []Revisioner
var tok token
var err error
for {
tok, _, err = p.scan()
if err != nil {
return nil, err
}
switch tok {
case at:
rev, err = p.parseAt()
case tilde:
rev, err = p.parseTilde()
case caret:
rev, err = p.parseCaret()
case colon:
rev, err = p.parseColon()
case eof:
err = p.validateFullRevision(&revs)
if err != nil {
return []Revisioner{}, err
}
return revs, nil
default:
p.unscan()
rev, err = p.parseRef()
}
if err != nil {
return []Revisioner{}, err
}
revs = append(revs, rev)
}
}
// validateFullRevision ensures all revisioner chunks make a valid revision
func (p *Parser) validateFullRevision(chunks *[]Revisioner) error {
var hasReference bool
for i, chunk := range *chunks {
switch chunk.(type) {
case Ref:
if i == 0 {
hasReference = true
} else {
return &ErrInvalidRevision{`reference must be defined once at the beginning`}
}
case AtDate:
if len(*chunks) == 1 || hasReference && len(*chunks) == 2 {
return nil
}
return &ErrInvalidRevision{`"@" statement is not valid, could be : <refname>@{<ISO-8601 date>}, @{<ISO-8601 date>}`}
case AtReflog:
if len(*chunks) == 1 || hasReference && len(*chunks) == 2 {
return nil
}
return &ErrInvalidRevision{`"@" statement is not valid, could be : <refname>@{<n>}, @{<n>}`}
case AtCheckout:
if len(*chunks) == 1 {
return nil
}
return &ErrInvalidRevision{`"@" statement is not valid, could be : @{-<n>}`}
case AtUpstream:
if len(*chunks) == 1 || hasReference && len(*chunks) == 2 {
return nil
}
return &ErrInvalidRevision{`"@" statement is not valid, could be : <refname>@{upstream}, @{upstream}, <refname>@{u}, @{u}`}
case AtPush:
if len(*chunks) == 1 || hasReference && len(*chunks) == 2 {
return nil
}
return &ErrInvalidRevision{`"@" statement is not valid, could be : <refname>@{push}, @{push}`}
case TildePath, CaretPath, CaretReg:
if !hasReference {
return &ErrInvalidRevision{`"~" or "^" statement must have a reference defined at the beginning`}
}
case ColonReg:
if len(*chunks) == 1 {
return nil
}
return &ErrInvalidRevision{`":" statement is not valid, could be : :/<regexp>`}
case ColonPath:
if i == len(*chunks)-1 && hasReference || len(*chunks) == 1 {
return nil
}
return &ErrInvalidRevision{`":" statement is not valid, could be : <revision>:<path>`}
case ColonStagePath:
if len(*chunks) == 1 {
return nil
}
return &ErrInvalidRevision{`":" statement is not valid, could be : :<n>:<path>`}
}
}
return nil
}
// parseAt extract @ statements
func (p *Parser) parseAt() (Revisioner, error) {
var tok, nextTok token
var lit, nextLit string
var err error
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
if tok != obrace {
p.unscan()
return Ref("HEAD"), nil
}
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
nextTok, nextLit, err = p.scan()
if err != nil {
return nil, err
}
switch {
case tok == word && (lit == "u" || lit == "upstream") && nextTok == cbrace:
return AtUpstream{}, nil
case tok == word && lit == "push" && nextTok == cbrace:
return AtPush{}, nil
case tok == number && nextTok == cbrace:
n, _ := strconv.Atoi(lit)
return AtReflog{n}, nil
case tok == minus && nextTok == number:
n, _ := strconv.Atoi(nextLit)
t, _, err := p.scan()
if err != nil {
return nil, err
}
if t != cbrace {
return nil, &ErrInvalidRevision{fmt.Sprintf(`missing "}" in @{-n} structure`)}
}
return AtCheckout{n}, nil
default:
p.unscan()
date := lit
for {
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
switch {
case tok == cbrace:
t, err := time.Parse("2006-01-02T15:04:05Z", date)
if err != nil {
return nil, &ErrInvalidRevision{fmt.Sprintf(`wrong date "%s" must fit ISO-8601 format : 2006-01-02T15:04:05Z`, date)}
}
return AtDate{t}, nil
default:
date += lit
}
}
}
}
// parseTilde extract ~ statements
func (p *Parser) parseTilde() (Revisioner, error) {
var tok token
var lit string
var err error
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
switch {
case tok == number:
n, _ := strconv.Atoi(lit)
return TildePath{n}, nil
default:
p.unscan()
return TildePath{1}, nil
}
}
// parseCaret extract ^ statements
func (p *Parser) parseCaret() (Revisioner, error) {
var tok token
var lit string
var err error
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
switch {
case tok == obrace:
r, err := p.parseCaretBraces()
if err != nil {
return nil, err
}
return r, nil
case tok == number:
n, _ := strconv.Atoi(lit)
if n > 2 {
return nil, &ErrInvalidRevision{fmt.Sprintf(`"%s" found must be 0, 1 or 2 after "^"`, lit)}
}
return CaretPath{n}, nil
default:
p.unscan()
return CaretPath{1}, nil
}
}
// parseCaretBraces extract ^{<data>} statements
func (p *Parser) parseCaretBraces() (Revisioner, error) {
var tok, nextTok token
var lit, _ string
start := true
var re string
var negate bool
var err error
for {
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
nextTok, _, err = p.scan()
if err != nil {
return nil, err
}
switch {
case tok == word && nextTok == cbrace && (lit == "commit" || lit == "tree" || lit == "blob" || lit == "tag" || lit == "object"):
return CaretType{lit}, nil
case re == "" && tok == cbrace:
return CaretType{"tag"}, nil
case re == "" && tok == emark && nextTok == emark:
re += lit
case re == "" && tok == emark && nextTok == minus:
negate = true
case re == "" && tok == emark:
return nil, &ErrInvalidRevision{fmt.Sprintf(`revision suffix brace component sequences starting with "/!" others than those defined are reserved`)}
case re == "" && tok == slash:
p.unscan()
case tok != slash && start:
return nil, &ErrInvalidRevision{fmt.Sprintf(`"%s" is not a valid revision suffix brace component`, lit)}
case tok != cbrace:
p.unscan()
re += lit
case tok == cbrace:
p.unscan()
reg, err := regexp.Compile(re)
if err != nil {
return CaretReg{}, &ErrInvalidRevision{fmt.Sprintf(`revision suffix brace component, %s`, err.Error())}
}
return CaretReg{reg, negate}, nil
}
start = false
}
}
// parseColon extract : statements
func (p *Parser) parseColon() (Revisioner, error) {
var tok token
var err error
tok, _, err = p.scan()
if err != nil {
return nil, err
}
switch tok {
case slash:
return p.parseColonSlash()
default:
p.unscan()
return p.parseColonDefault()
}
}
// parseColonSlash extract :/<data> statements
func (p *Parser) parseColonSlash() (Revisioner, error) {
var tok, nextTok token
var lit string
var re string
var negate bool
var err error
for {
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
nextTok, _, err = p.scan()
if err != nil {
return nil, err
}
switch {
case tok == emark && nextTok == emark:
re += lit
case re == "" && tok == emark && nextTok == minus:
negate = true
case re == "" && tok == emark:
return nil, &ErrInvalidRevision{fmt.Sprintf(`revision suffix brace component sequences starting with "/!" others than those defined are reserved`)}
case tok == eof:
p.unscan()
reg, err := regexp.Compile(re)
if err != nil {
return ColonReg{}, &ErrInvalidRevision{fmt.Sprintf(`revision suffix brace component, %s`, err.Error())}
}
return ColonReg{reg, negate}, nil
default:
p.unscan()
re += lit
}
}
}
// parseColonDefault extract :<data> statements
func (p *Parser) parseColonDefault() (Revisioner, error) {
var tok token
var lit string
var path string
var stage int
var err error
var n = -1
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
nextTok, _, err := p.scan()
if err != nil {
return nil, err
}
if tok == number && nextTok == colon {
n, _ = strconv.Atoi(lit)
}
switch n {
case 0, 1, 2, 3:
stage = n
default:
path += lit
p.unscan()
}
for {
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
switch {
case tok == eof && n == -1:
return ColonPath{path}, nil
case tok == eof:
return ColonStagePath{path, stage}, nil
default:
path += lit
}
}
}
// parseRef extract reference name
func (p *Parser) parseRef() (Revisioner, error) {
var tok, prevTok token
var lit, buf string
var endOfRef bool
var err error
for {
tok, lit, err = p.scan()
if err != nil {
return nil, err
}
switch tok {
case eof, at, colon, tilde, caret:
endOfRef = true
}
err := p.checkRefFormat(tok, lit, prevTok, buf, endOfRef)
if err != nil {
return "", err
}
if endOfRef {
p.unscan()
return Ref(buf), nil
}
buf += lit
prevTok = tok
}
}
// checkRefFormat ensure reference name follow rules defined here :
// https://git-scm.com/docs/git-check-ref-format
func (p *Parser) checkRefFormat(token token, literal string, previousToken token, buffer string, endOfRef bool) error {
switch token {
case aslash, space, control, qmark, asterisk, obracket:
return &ErrInvalidRevision{fmt.Sprintf(`must not contains "%s"`, literal)}
}
switch {
case (token == dot || token == slash) && buffer == "":
return &ErrInvalidRevision{fmt.Sprintf(`must not start with "%s"`, literal)}
case previousToken == slash && endOfRef:
return &ErrInvalidRevision{`must not end with "/"`}
case previousToken == dot && endOfRef:
return &ErrInvalidRevision{`must not end with "."`}
case token == dot && previousToken == slash:
return &ErrInvalidRevision{`must not contains "/."`}
case previousToken == dot && token == dot:
return &ErrInvalidRevision{`must not contains ".."`}
case previousToken == slash && token == slash:
return &ErrInvalidRevision{`must not contains consecutively "/"`}
case (token == slash || endOfRef) && len(buffer) > 4 && buffer[len(buffer)-5:] == ".lock":
return &ErrInvalidRevision{"cannot end with .lock"}
}
return nil
}
