1 files changed, 89 insertions, 0 deletions
diff --git a/src/sksl/lex/RegexParser.h b/src/sksl/lex/RegexParser.h
new file mode 100644
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+++ b/src/sksl/lex/RegexParser.h
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+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SKSL_REGEXPARSER
+#define SKSL_REGEXPARSER
+
+#include "RegexNode.h"
+
+#include <stack>
+#include <string>
+
+/**
+ * Turns a simple regular expression into a parse tree. The regular expression syntax supports only
+ * the basic quantifiers ('*', '+', and '?'), alternation ('|'), character sets ('[a-z]'), and
+ * groups ('()').
+ */
+class RegexParser {
+public:
+    RegexNode parse(std::string source);
+
+private:
+    static constexpr char END = '\0';
+
+    char peek();
+
+    void expect(char c);
+
+    RegexNode pop();
+
+    /**
+     * Matches a char literal, parenthesized group, character set, or dot ('.').
+     */
+    void term();
+
+    /**
+     * Matches a term followed by an optional quantifier ('*', '+', or '?').
+     */
+    void quantifiedTerm();
+
+    /**
+     * Matches a sequence of quantifiedTerms.
+     */
+    void sequence();
+
+    /**
+     * Returns a node representing the given escape character (e.g. escapeSequence('n') returns a
+     * node which matches a newline character).
+     */
+    RegexNode escapeSequence(char c);
+
+    /**
+     * Matches a literal character or escape sequence.
+     */
+    void literal();
+
+    /**
+     * Matches a dot ('.').
+     */
+    void dot();
+
+    /**
+     * Matches a parenthesized group.
+     */
+    void group();
+
+    /**
+     * Matches a literal character, escape sequence, or character range from a character set.
+     */
+    void setItem();
+
+    /**
+     * Matches a character set.
+     */
+    void set();
+
+    void regex();
+
+    std::string fSource;
+
+    size_t fIndex;
+
+    std::stack<RegexNode> fStack;
+};
+
+#endif