Move MatchPattern to its own header and the base namespace.

base/strings/pattern.cc

Index: base/strings/pattern.cc
diff --git a/base/strings/pattern.cc b/base/strings/pattern.cc
new file mode 100644
index 0000000000000000000000000000000000000000..8739c95637a462a1f860eeeb5a431f4062d31398
--- /dev/null
+++ b/base/strings/pattern.cc
@@ -0,0 +1,169 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/strings/pattern.h"
+
+#include "base/third_party/icu/icu_utf.h"
+
+namespace base {
+
+namespace {
+
+static bool IsWildcard(base_icu::UChar32 character) {
+  return character == '*' || character == '?';
+}
+
+// Move the strings pointers to the point where they start to differ.
+template <typename CHAR, typename NEXT>
+static void EatSameChars(const CHAR** pattern, const CHAR* pattern_end,
+                         const CHAR** string, const CHAR* string_end,
+                         NEXT next) {
+  const CHAR* escape = NULL;
+  while (*pattern != pattern_end && *string != string_end) {
+    if (!escape && IsWildcard(**pattern)) {
+      // We don't want to match wildcard here, except if it's escaped.
+      return;
+    }
+
+    // Check if the escapement char is found. If so, skip it and move to the
+    // next character.
+    if (!escape && **pattern == '\\') {
+      escape = *pattern;
+      next(pattern, pattern_end);
+      continue;
+    }
+
+    // Check if the chars match, if so, increment the ptrs.
+    const CHAR* pattern_next = *pattern;
+    const CHAR* string_next = *string;
+    base_icu::UChar32 pattern_char = next(&pattern_next, pattern_end);
+    if (pattern_char == next(&string_next, string_end) &&
+        pattern_char != CBU_SENTINEL) {
+      *pattern = pattern_next;
+      *string = string_next;
+    } else {
+      // Uh oh, it did not match, we are done. If the last char was an
+      // escapement, that means that it was an error to advance the ptr here,
+      // let's put it back where it was. This also mean that the MatchPattern
+      // function will return false because if we can't match an escape char
+      // here, then no one will.
+      if (escape) {
+        *pattern = escape;
+      }
+      return;
+    }
+
+    escape = NULL;
+  }
+}
+
+template <typename CHAR, typename NEXT>
+static void EatWildcard(const CHAR** pattern, const CHAR* end, NEXT next) {
+  while (*pattern != end) {
+    if (!IsWildcard(**pattern))
+      return;
+    next(pattern, end);
+  }
+}
+
+template <typename CHAR, typename NEXT>
+static bool MatchPatternT(const CHAR* eval, const CHAR* eval_end,
+                          const CHAR* pattern, const CHAR* pattern_end,
+                          int depth,
+                          NEXT next) {
+  const int kMaxDepth = 16;
+  if (depth > kMaxDepth)
+    return false;
+
+  // Eat all the matching chars.
+  EatSameChars(&pattern, pattern_end, &eval, eval_end, next);
+
+  // If the string is empty, then the pattern must be empty too, or contains
+  // only wildcards.
+  if (eval == eval_end) {
+    EatWildcard(&pattern, pattern_end, next);
+    return pattern == pattern_end;
+  }
+
+  // Pattern is empty but not string, this is not a match.
+  if (pattern == pattern_end)
+    return false;
+
+  // If this is a question mark, then we need to compare the rest with
+  // the current string or the string with one character eaten.
+  const CHAR* next_pattern = pattern;
+  next(&next_pattern, pattern_end);
+  if (pattern[0] == '?') {
+    if (MatchPatternT(eval, eval_end, next_pattern, pattern_end,
+                      depth + 1, next))
+      return true;
+    const CHAR* next_eval = eval;
+    next(&next_eval, eval_end);
+    if (MatchPatternT(next_eval, eval_end, next_pattern, pattern_end,
+                      depth + 1, next))
+      return true;
+  }
+
+  // This is a *, try to match all the possible substrings with the remainder
+  // of the pattern.
+  if (pattern[0] == '*') {
+    // Collapse duplicate wild cards (********** into *) so that the
+    // method does not recurse unnecessarily. http://crbug.com/52839
+    EatWildcard(&next_pattern, pattern_end, next);
+
+    while (eval != eval_end) {
+      if (MatchPatternT(eval, eval_end, next_pattern, pattern_end,
+                        depth + 1, next))
+        return true;
+      eval++;
+    }
+
+    // We reached the end of the string, let see if the pattern contains only
+    // wildcards.
+    if (eval == eval_end) {
+      EatWildcard(&pattern, pattern_end, next);
+      if (pattern != pattern_end)
+        return false;
+      return true;
+    }
+  }
+
+  return false;
+}
+
+struct NextCharUTF8 {
+  base_icu::UChar32 operator()(const char** p, const char* end) {
+    base_icu::UChar32 c;
+    int offset = 0;
+    CBU8_NEXT(*p, offset, end - *p, c);
+    *p += offset;
+    return c;
+  }
+};
+
+struct NextCharUTF16 {
+  base_icu::UChar32 operator()(const char16** p, const char16* end) {
+    base_icu::UChar32 c;
+    int offset = 0;
+    CBU16_NEXT(*p, offset, end - *p, c);
+    *p += offset;
+    return c;
+  }
+};
+
+}  // namespace
+
+bool MatchPattern(const StringPiece& eval, const StringPiece& pattern) {
+  return MatchPatternT(eval.data(), eval.data() + eval.size(),
+                       pattern.data(), pattern.data() + pattern.size(),
+                       0, NextCharUTF8());
+}
+
+bool MatchPattern(const StringPiece16& eval, const StringPiece16& pattern) {
+  return MatchPatternT(eval.data(), eval.data() + eval.size(),
+                       pattern.data(), pattern.data() + pattern.size(),
+                       0, NextCharUTF16());
+}
+
+}  // namespace base