[ignore] Add extensive test for gitignore matching

.travis.yml

@@ -3,6 +3,7 @@ language: rust
 env:
   global:
     - PROJECT_NAME=ripgrep
+    - RUST_BACKTRACE: full
 matrix:
   include:
     # Nightly channel.

appveyor.yml

@@ -1,6 +1,7 @@
 environment:
   global:
     PROJECT_NAME: ripgrep
+    RUST_BACKTRACE: full
   matrix:
     - TARGET: i686-pc-windows-gnu
       CHANNEL: stable

ignore/src/gitignore.rs

@@ -169,8 +169,8 @@ impl Gitignore {
         self.num_whitelists
     }
 
-    /// Returns whether the given file path matched a pattern in this gitignore
-    /// matcher.
+    /// Returns whether the given path (file or directory) matched a pattern in
+    /// this gitignore matcher.
     ///
     /// `is_dir` should be true if the path refers to a directory and false
     /// otherwise.
@@ -191,6 +191,46 @@ impl Gitignore {
         self.matched_stripped(self.strip(path.as_ref()), is_dir)
     }
 
+    /// Returns whether the given path (file or directory, and expected to be
+    /// under the root) or any of its parent directories (up to the root)
+    /// matched a pattern in this gitignore matcher.
+    ///
+    /// NOTE: This method is more expensive than walking the directory hierarchy
+    /// top-to-bottom and matching the entries. But, is easier to use in cases
+    /// when a list of paths are available without a hierarchy.
+    ///
+    /// `is_dir` should be true if the path refers to a directory and false
+    /// otherwise.
+    ///
+    /// The given path is matched relative to the path given when building
+    /// the matcher. Specifically, before matching `path`, its prefix (as
+    /// determined by a common suffix of the directory containing this
+    /// gitignore) is stripped. If there is no common suffix/prefix overlap,
+    /// then `path` is assumed to be relative to this matcher.
+    pub fn matched_path_or_any_parents<P: AsRef<Path>>(
+        &self,
+        path: P,
+        is_dir: bool,
+    ) -> Match<&Glob> {
+        if self.is_empty() {
+            return Match::None;
+        }
+        let mut path = self.strip(path.as_ref());
+        debug_assert!(
+            !path.has_root(),
+            "path is expect to be under the root"
+        );
+        loop {
+            match self.matched_stripped(path, is_dir) {
+                Match::None => match path.parent() {
+                    Some(parent) => path = parent,
+                    None => return Match::None,
+                },
+                a_match => return a_match,
+            }
+        }
+    }
+
     /// Like matched, but takes a path that has already been stripped.
     fn matched_stripped<P: AsRef<Path>>(
         &self,
@@ -440,7 +480,7 @@ impl GitignoreBuilder {
     }
 
     /// Toggle whether the globs should be matched case insensitively or not.
-    /// 
+    ///
     /// This is disabled by default.
     pub fn case_insensitive(
         &mut self, yes: bool

ignore/tests/gitignore_matched_path_or_any_parents_tests.gitignore

@@ -0,0 +1,216 @@
+# Based on https://github.com/behnam/gitignore-test/blob/master/.gitignore
+
+### file in root
+
+# MATCH /file_root_1
+file_root_00
+
+# NO_MATCH
+file_root_01/
+
+# NO_MATCH
+file_root_02/*
+
+# NO_MATCH
+file_root_03/**
+
+
+# MATCH /file_root_10
+/file_root_10
+
+# NO_MATCH
+/file_root_11/
+
+# NO_MATCH
+/file_root_12/*
+
+# NO_MATCH
+/file_root_13/**
+
+
+# NO_MATCH
+*/file_root_20
+
+# NO_MATCH
+*/file_root_21/
+
+# NO_MATCH
+*/file_root_22/*
+
+# NO_MATCH
+*/file_root_23/**
+
+
+# MATCH /file_root_30
+**/file_root_30
+
+# NO_MATCH
+**/file_root_31/
+
+# NO_MATCH
+**/file_root_32/*
+
+# NO_MATCH
+**/file_root_33/**
+
+
+### file in sub-dir
+
+# MATCH /parent_dir/file_deep_1
+file_deep_00
+
+# NO_MATCH
+file_deep_01/
+
+# NO_MATCH
+file_deep_02/*
+
+# NO_MATCH
+file_deep_03/**
+
+
+# NO_MATCH
+/file_deep_10
+
+# NO_MATCH
+/file_deep_11/
+
+# NO_MATCH
+/file_deep_12/*
+
+# NO_MATCH
+/file_deep_13/**
+
+
+# MATCH /parent_dir/file_deep_20
+*/file_deep_20
+
+# NO_MATCH
+*/file_deep_21/
+
+# NO_MATCH
+*/file_deep_22/*
+
+# NO_MATCH
+*/file_deep_23/**
+
+
+# MATCH /parent_dir/file_deep_30
+**/file_deep_30
+
+# NO_MATCH
+**/file_deep_31/
+
+# NO_MATCH
+**/file_deep_32/*
+
+# NO_MATCH
+**/file_deep_33/**
+
+
+### dir in root
+
+# MATCH /dir_root_00
+dir_root_00
+
+# MATCH /dir_root_01
+dir_root_01/
+
+# MATCH /dir_root_02
+dir_root_02/*
+
+# MATCH /dir_root_03
+dir_root_03/**
+
+
+# MATCH /dir_root_10
+/dir_root_10
+
+# MATCH /dir_root_11
+/dir_root_11/
+
+# MATCH /dir_root_12
+/dir_root_12/*
+
+# MATCH /dir_root_13
+/dir_root_13/**
+
+
+# NO_MATCH
+*/dir_root_20
+
+# NO_MATCH
+*/dir_root_21/
+
+# NO_MATCH
+*/dir_root_22/*
+
+# NO_MATCH
+*/dir_root_23/**
+
+
+# MATCH /dir_root_30
+**/dir_root_30
+
+# MATCH /dir_root_31
+**/dir_root_31/
+
+# MATCH /dir_root_32
+**/dir_root_32/*
+
+# MATCH /dir_root_33
+**/dir_root_33/**
+
+
+### dir in sub-dir
+
+# MATCH /parent_dir/dir_deep_00
+dir_deep_00
+
+# MATCH /parent_dir/dir_deep_01
+dir_deep_01/
+
+# NO_MATCH
+dir_deep_02/*
+
+# NO_MATCH
+dir_deep_03/**
+
+
+# NO_MATCH
+/dir_deep_10
+
+# NO_MATCH
+/dir_deep_11/
+
+# NO_MATCH
+/dir_deep_12/*
+
+# NO_MATCH
+/dir_deep_13/**
+
+
+# MATCH /parent_dir/dir_deep_20
+*/dir_deep_20
+
+# MATCH /parent_dir/dir_deep_21
+*/dir_deep_21/
+
+# MATCH /parent_dir/dir_deep_22
+*/dir_deep_22/*
+
+# MATCH /parent_dir/dir_deep_23
+*/dir_deep_23/**
+
+
+# MATCH /parent_dir/dir_deep_30
+**/dir_deep_30
+
+# MATCH /parent_dir/dir_deep_31
+**/dir_deep_31/
+
+# MATCH /parent_dir/dir_deep_32
+**/dir_deep_32/*
+
+# MATCH /parent_dir/dir_deep_33
+**/dir_deep_33/**