embed go-gitignore to lib

README.md

@@ -157,6 +157,7 @@ We are working on it, but it's not an urgent task. If you really need it, PR is
 
 - [husky](https://github.com/typicode/husky/tree/main)
 - [lint-staged](https://github.com/okonet/lint-staged)
+- [go-gitignore](https://github.com/sabhiram/go-gitignore)
 
 ## License
 

internal/lib/gitignore/ignore.go

@@ -0,0 +1,240 @@
+/*
+Package 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 ignore
+
+import (
+	"io/ioutil"
+	"os"
+	"regexp"
+	"strings"
+)
+
+////////////////////////////////////////////////////////////
+
+// IgnoreParser is an interface with `MatchesPaths`.
+type IgnoreParser interface {
+	MatchesPath(f string) bool
+	MatchesPathHow(f string) (bool, *IgnorePattern)
+}
+
+////////////////////////////////////////////////////////////
+
+// 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
+	LineNo  int
+	Line    string
+}
+
+// GitIgnore wraps a list of ignore pattern.
+type GitIgnore struct {
+	patterns []*IgnorePattern
+}
+
+// CompileIgnoreLines accepts a variadic set of strings, and returns a GitIgnore
+// instance 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 {
+	gi := &GitIgnore{}
+	for i, line := range lines {
+		pattern, negatePattern := getPatternFromLine(line)
+		if pattern != nil {
+			// LineNo is 1-based numbering to match `git check-ignore -v` output
+			ip := &IgnorePattern{pattern, negatePattern, i + 1, line}
+			gi.patterns = append(gi.patterns, ip)
+		}
+	}
+	return gi
+}
+
+// CompileIgnoreFile uses an ignore file as the input, parses the lines out of
+// the file and invokes the CompileIgnoreLines method.
+func CompileIgnoreFile(fpath string) (*GitIgnore, error) {
+	bs, err := ioutil.ReadFile(fpath)
+	if err != nil {
+		return nil, err
+	}
+
+	s := strings.Split(string(bs), "\n")
+	return CompileIgnoreLines(s...), nil
+}
+
+// CompileIgnoreFileAndLines 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) {
+	bs, err := ioutil.ReadFile(fpath)
+	if err != nil {
+		return nil, err
+	}
+
+	gi := CompileIgnoreLines(append(strings.Split(string(bs), "\n"), lines...)...)
+	return gi, nil
+}
+
+////////////////////////////////////////////////////////////
+
+// MatchesPath returns true if the given GitIgnore structure would target
+// a given path string `f`.
+func (gi *GitIgnore) MatchesPath(f string) bool {
+	matchesPath, _ := gi.MatchesPathHow(f)
+	return matchesPath
+}
+
+// MatchesPathHow returns true, `pattern` if the given GitIgnore structure would target
+// a given path string `f`.
+// The IgnorePattern has the Line, LineNo fields.
+func (gi *GitIgnore) MatchesPathHow(f string) (bool, *IgnorePattern) {
+	// Replace OS-specific path separator.
+	f = strings.Replace(f, string(os.PathSeparator), "/", -1)
+
+	matchesPath := false
+	var mip *IgnorePattern
+	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
+				mip = ip
+			} else if matchesPath {
+				// Negated pattern, and matchesPath is already set
+				matchesPath = false
+			}
+		}
+	}
+	return matchesPath, mip
+}
+
+////////////////////////////////////////////////////////////