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Copy pathgitignore.go
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224 lines (191 loc) · 8.02 KB
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/*
ignore is a library which returns a new ignorer object which can
test against various paths. This is particularly useful when trying
to filter files based on a .gitignore document
The rules for parsing the input file are the same as the ones listed
in the Git docs here: http://git-scm.com/docs/gitignore
The summarized version of the same has been copied here:
1. A blank line matches no files, so it can serve as a separator
for readability.
2. A line starting with # serves as a comment. Put a backslash ("\")
in front of the first hash for patterns that begin with a hash.
3. Trailing spaces are ignored unless they are quoted with backslash ("\").
4. An optional prefix "!" which negates the pattern; any matching file
excluded by a previous pattern will become included again. It is not
possible to re-include a file if a parent directory of that file is
excluded. Git doesn’t list excluded directories for performance reasons,
so any patterns on contained files have no effect, no matter where they
are defined. Put a backslash ("\") in front of the first "!" for
patterns that begin with a literal "!", for example, "\!important!.txt".
5. If the pattern ends with a slash, it is removed for the purpose of the
following description, but it would only find a match with a directory.
In other words, foo/ will match a directory foo and paths underneath it,
but will not match a regular file or a symbolic link foo (this is
consistent with the way how pathspec works in general in Git).
6. If the pattern does not contain a slash /, Git treats it as a shell glob
pattern and checks for a match against the pathname relative to the
location of the .gitignore file (relative to the toplevel of the work
tree if not from a .gitignore file).
7. Otherwise, Git treats the pattern as a shell glob suitable for
consumption by fnmatch(3) with the FNM_PATHNAME flag: wildcards in the
pattern will not match a / in the pathname. For example,
"Documentation/*.html" matches "Documentation/git.html" but not
"Documentation/ppc/ppc.html" or "tools/perf/Documentation/perf.html".
8. A leading slash matches the beginning of the pathname. For example,
"/*.c" matches "cat-file.c" but not "mozilla-sha1/sha1.c".
9. Two consecutive asterisks ("**") in patterns matched against full
pathname may have special meaning:
i. A leading "**" followed by a slash means match in all directories.
For example, "** /foo" matches file or directory "foo" anywhere,
the same as pattern "foo". "** /foo/bar" matches file or directory
"bar" anywhere that is directly under directory "foo".
ii. A trailing "/**" matches everything inside. For example, "abc/**"
matches all files inside directory "abc", relative to the location
of the .gitignore file, with infinite depth.
iii. A slash followed by two consecutive asterisks then a slash matches
zero or more directories. For example, "a/** /b" matches "a/b",
"a/x/b", "a/x/y/b" and so on.
iv. Other consecutive asterisks are considered invalid. */
package gateway
import (
"io/ioutil"
"os"
"regexp"
"strings"
)
////////////////////////////////////////////////////////////
// An IgnoreParser is an interface which exposes a single method:
// MatchesPath() - Returns true if the path is targeted by the patterns compiled
// in the GitIgnore structure
type IgnoreParser interface {
MatchesPath(f string) bool
}
////////////////////////////////////////////////////////////
// This function pretty much attempts to mimic the parsing rules
// listed above at the start of this file
func getPatternFromLine(line string) (*regexp.Regexp, bool) {
// Trim OS-specific carriage returns.
line = strings.TrimRight(line, "\r")
// Strip comments [Rule 2]
if strings.HasPrefix(line, `#`) {
return nil, false
}
// Trim string [Rule 3]
// TODO: Handle [Rule 3], when the " " is escaped with a \
line = strings.Trim(line, " ")
// Exit for no-ops and return nil which will prevent us from
// appending a pattern against this line
if line == "" {
return nil, false
}
// TODO: Handle [Rule 4] which negates the match for patterns leading with "!"
negatePattern := false
if line[0] == '!' {
negatePattern = true
line = line[1:]
}
// Handle [Rule 2, 4], when # or ! is escaped with a \
// Handle [Rule 4] once we tag negatePattern, strip the leading ! char
if regexp.MustCompile(`^(\#|\!)`).MatchString(line) {
line = line[1:]
}
// If we encounter a foo/*.blah in a folder, prepend the / char
if regexp.MustCompile(`([^\/+])/.*\*\.`).MatchString(line) && line[0] != '/' {
line = "/" + line
}
// Handle escaping the "." char
line = regexp.MustCompile(`\.`).ReplaceAllString(line, `\.`)
magicStar := "#$~"
// Handle "/**/" usage
if strings.HasPrefix(line, "/**/") {
line = line[1:]
}
line = regexp.MustCompile(`/\*\*/`).ReplaceAllString(line, `(/|/.+/)`)
line = regexp.MustCompile(`\*\*/`).ReplaceAllString(line, `(|.`+magicStar+`/)`)
line = regexp.MustCompile(`/\*\*`).ReplaceAllString(line, `(|/.`+magicStar+`)`)
// Handle escaping the "*" char
line = regexp.MustCompile(`\\\*`).ReplaceAllString(line, `\`+magicStar)
line = regexp.MustCompile(`\*`).ReplaceAllString(line, `([^/]*)`)
// Handle escaping the "?" char
line = strings.Replace(line, "?", `\?`, -1)
line = strings.Replace(line, magicStar, "*", -1)
// Temporary regex
var expr = ""
if strings.HasSuffix(line, "/") {
expr = line + "(|.*)$"
} else {
expr = line + "(|/.*)$"
}
if strings.HasPrefix(expr, "/") {
expr = "^(|/)" + expr[1:]
} else {
expr = "^(|.*/)" + expr
}
pattern, _ := regexp.Compile(expr)
return pattern, negatePattern
}
////////////////////////////////////////////////////////////
// ignorePattern encapsulates a pattern and if it is a negated pattern.
type ignorePattern struct {
pattern *regexp.Regexp
negate bool
}
// GitIgnore wraps a list of ignore pattern.
type GitIgnore struct {
patterns []*ignorePattern
}
// Accepts a variadic set of strings, and returns a GitIgnore object which
// converts and appends the lines in the input to regexp.Regexp patterns
// held within the GitIgnore objects "patterns" field
func CompileIgnoreLines(lines ...string) (*GitIgnore, error) {
gi := &GitIgnore{}
for _, line := range lines {
pattern, negatePattern := getPatternFromLine(line)
if pattern != nil {
ip := &ignorePattern{pattern, negatePattern}
gi.patterns = append(gi.patterns, ip)
}
}
return gi, nil
}
// Accepts a ignore file as the input, parses the lines out of the file
// and invokes the CompileIgnoreLines method
func CompileIgnoreFile(fpath string) (*GitIgnore, error) {
buffer, error := ioutil.ReadFile(fpath)
if error == nil {
s := strings.Split(string(buffer), "\n")
return CompileIgnoreLines(s...)
}
return CompileIgnoreLines("")
}
// Accepts a ignore file as the input, parses the lines out of the file
// and invokes the CompileIgnoreLines method with additional lines
func CompileIgnoreFileAndLines(fpath string, lines ...string) (*GitIgnore, error) {
buffer, error := ioutil.ReadFile(fpath)
if error == nil {
s := strings.Split(string(buffer), "\n")
return CompileIgnoreLines(append(s, lines...)...)
}
return nil, error
}
////////////////////////////////////////////////////////////
// MatchesPath returns true if the given GitIgnore structure would target
// a given path string `f`.
func (gi *GitIgnore) MatchesPath(f string) bool {
// Replace OS-specific path separator.
f = strings.Replace(f, string(os.PathSeparator), "/", -1)
matchesPath := false
for _, ip := range gi.patterns {
if ip.pattern.MatchString(f) {
// If this is a regular target (not negated with a gitignore exclude "!" etc)
if !ip.negate {
matchesPath = true
} else if matchesPath {
// Negated pattern, and matchesPath is already set
matchesPath = false
}
}
}
return matchesPath
}
////////////////////////////////////////////////////////////