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