AK: Add a GenericLexer and extend the JsonParser with it (#2696)

AK/GenericLexer.h

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2020, Benoit Lormeau <blormeau@outlook.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Function.h>
+#include <AK/StringView.h>
+
+namespace AK {
+
+class GenericLexer {
+public:
+    explicit GenericLexer(const StringView& input);
+    virtual ~GenericLexer();
+
+    using Condition = Function<bool(char)>;
+
+    size_t tell() const { return m_index; }
+    size_t tell_remaining() const { return m_input.length() - m_index; }
+
+    bool is_eof() const;
+
+    char peek(size_t offset = 0) const;
+
+    bool next_is(char expected) const;
+    bool next_is(const char* expected) const;
+    bool next_is(Condition) const;
+
+    char consume();
+    bool consume_specific(char specific);
+    bool consume_specific(const char* str);
+    StringView consume(size_t count);
+    StringView consume_all();
+    StringView consume_line();
+    StringView consume_while(Condition);
+    StringView consume_until(char stop);
+    StringView consume_until(const char* stop);
+    StringView consume_until(Condition);
+    // FIXME: provide an escape character
+    StringView consume_quoted_string();
+
+    void ignore(size_t count = 1);
+    void ignore_while(Condition);
+    void ignore_until(char stop);
+    void ignore_until(const char* stop);
+    void ignore_until(Condition);
+
+protected:
+    StringView m_input;
+    size_t m_index { 0 };
+};
+
+// ctype adaptors
+// FIXME: maybe put them in an another file?
+bool is_alpha(char);
+bool is_alphanum(char);
+bool is_control(char);
+bool is_digit(char);
+bool is_graphic(char);
+bool is_hex_digit(char);
+bool is_lowercase(char);
+bool is_path_separator(char);
+bool is_printable(char);
+bool is_punctuation(char);
+bool is_quote(char);
+bool is_uppercase(char);
+bool is_whitespace(char);
+
+}
+
+using AK::GenericLexer;
+
+using AK::is_alpha;
+using AK::is_alphanum;
+using AK::is_control;
+using AK::is_digit;
+using AK::is_graphic;
+using AK::is_hex_digit;
+using AK::is_lowercase;
+using AK::is_path_separator;
+using AK::is_printable;
+using AK::is_punctuation;
+using AK::is_quote;
+using AK::is_uppercase;
+using AK::is_whitespace;