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

AK/GenericLexer.cpp

@@ -0,0 +1,335 @@
+/*
+ * 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.
+ */
+
+#include <AK/Assertions.h>
+#include <AK/GenericLexer.h>
+
+namespace AK {
+
+GenericLexer::GenericLexer(const StringView& input)
+    : m_input(input)
+{
+}
+
+GenericLexer::~GenericLexer()
+{
+}
+
+// Tells whether the parser's index has reached input's end
+bool GenericLexer::is_eof() const
+{
+    return m_index >= m_input.length();
+}
+
+// Returns the current character at the parser index, plus `offset` if specified
+char GenericLexer::peek(size_t offset) const
+{
+    return (m_index + offset < m_input.length()) ? m_input[m_index + offset] : '\0';
+}
+
+// Tests the next character in the input
+bool GenericLexer::next_is(char expected) const
+{
+    return peek() == expected;
+}
+
+// Tests if the `expected` string comes next in the input
+bool GenericLexer::next_is(const char* expected) const
+{
+    for (size_t i = 0; expected[i] != '\0'; ++i)
+        if (peek(i) != expected[i])
+            return false;
+    return true;
+}
+
+// Tests the next character against a Condition
+bool GenericLexer::next_is(Condition condition) const
+{
+    return condition(peek());
+}
+
+// Consume a character and advance the parser index
+char GenericLexer::consume()
+{
+    ASSERT(!is_eof());
+    return m_input[m_index++];
+}
+
+// Consume the given character if it is next in the input
+bool GenericLexer::consume_specific(char specific)
+{
+    if (peek() != specific)
+        return false;
+
+    ignore();
+    return true;
+}
+
+// Consume the given string if it is next in the input
+bool GenericLexer::consume_specific(const char* str)
+{
+    if (!next_is(str))
+        return false;
+
+    ignore(__builtin_strlen(str));
+    return true;
+}
+
+// Consume a number of characters
+StringView GenericLexer::consume(size_t count)
+{
+    if (count == 0)
+        return {};
+
+    size_t start = m_index;
+    size_t length = min(count, m_input.length() - m_index);
+    m_index += length;
+
+    return m_input.substring_view(start, length);
+}
+
+// Consume the rest of the input
+StringView GenericLexer::consume_all()
+{
+    if (is_eof())
+        return {};
+
+    auto rest = m_input.substring_view(m_index, m_input.length() - m_index);
+    m_index = m_input.length();
+    return rest;
+}
+
+// Consume until a new line is found
+StringView GenericLexer::consume_line()
+{
+    size_t start = m_index;
+    while (!is_eof() && peek() != '\r' && peek() != '\n')
+        m_index++;
+    size_t length = m_index - start;
+
+    consume_specific('\r');
+    consume_specific('\n');
+
+    if (length == 0)
+        return {};
+    return m_input.substring_view(start, length);
+}
+
+// Consume and return characters while `condition` returns true
+StringView GenericLexer::consume_while(Condition condition)
+{
+    size_t start = m_index;
+    while (!is_eof() && condition(peek()))
+        m_index++;
+    size_t length = m_index - start;
+
+    if (length == 0)
+        return {};
+    return m_input.substring_view(start, length);
+}
+
+// Consume and return characters until `stop` is peek'd
+// The `stop` character is ignored, as it is user-defined
+StringView GenericLexer::consume_until(char stop)
+{
+    size_t start = m_index;
+    while (!is_eof() && peek() != stop)
+        m_index++;
+    size_t length = m_index - start;
+
+    ignore();
+
+    if (length == 0)
+        return {};
+    return m_input.substring_view(start, length);
+}
+
+// Consume and return characters until the string `stop` is found
+// The `stop` string is ignored, as it is user-defined
+StringView GenericLexer::consume_until(const char* stop)
+{
+    size_t start = m_index;
+    while (!is_eof() && !next_is(stop))
+        m_index++;
+    size_t length = m_index - start;
+
+    ignore(__builtin_strlen(stop));
+
+    if (length == 0)
+        return {};
+    return m_input.substring_view(start, length);
+}
+
+// Consume and return characters until `condition` return true
+StringView GenericLexer::consume_until(Condition condition)
+{
+    size_t start = m_index;
+    while (!is_eof() && !condition(peek()))
+        m_index++;
+    size_t length = m_index - start;
+
+    if (length == 0)
+        return {};
+    return m_input.substring_view(start, length);
+}
+
+// Consume a string surrounded by single or double quotes
+// The returned StringView does not include the quotes
+StringView GenericLexer::consume_quoted_string()
+{
+    if (!is_quote(peek()))
+        return {};
+
+    char quote_char = consume();
+    size_t start = m_index;
+    while (!is_eof() && peek() != quote_char)
+        m_index++;
+    size_t length = m_index - start;
+
+    if (peek() != quote_char) {
+        m_index = start - 1; // Restore the index in case the string is unterminated
+        return {};
+    }
+
+    ignore();
+
+    return m_input.substring_view(start, length);
+}
+
+// Ignore a number of characters (1 by default)
+void GenericLexer::ignore(size_t count)
+{
+    count = min(count, m_input.length() - m_index);
+    m_index += count;
+}
+
+// Ignore characters while `condition` returns true
+void GenericLexer::ignore_while(Condition condition)
+{
+    while (!is_eof() && condition(peek()))
+        m_index++;
+}
+
+// Ignore characters until `stop` is peek'd
+// The `stop` character is ignored as it is user-defined
+void GenericLexer::ignore_until(char stop)
+{
+    while (!is_eof() && peek() != stop)
+        m_index++;
+
+    ignore();
+}
+
+// Ignore characters until the string `stop` is found
+// The `stop` string is ignored, as it is user-defined
+void GenericLexer::ignore_until(const char* stop)
+{
+    while (!is_eof() && !next_is(stop))
+        m_index++;
+
+    ignore(__builtin_strlen(stop));
+}
+
+// Ignore characters until `condition` return true
+// We don't skip the stop character as it may not be a single value
+void GenericLexer::ignore_until(Condition condition)
+{
+    while (!is_eof() && !condition(peek()))
+        m_index++;
+}
+
+
+bool is_control(char c)
+{
+    return (c >= 0 && c <= 31) || c == 127;
+}
+
+bool is_whitespace(char c)
+{
+    return (c >= '\t' && c <= '\r') || c == ' ';
+}
+
+bool is_lowercase(char c)
+{
+    return c >= 'a' && c <= 'z';
+}
+
+bool is_uppercase(char c)
+{
+    return c >= 'A' && c <= 'Z';
+}
+
+bool is_digit(char c)
+{
+    return c >= '0' && c <= '9';
+}
+
+bool is_punctuation(char c)
+{
+    return (c >= '!' && c <= '/')
+        || (c >= ':' && c <= '@')
+        || (c >= '[' && c <= '`')
+        || (c >= '{' && c <= '~');
+}
+
+bool is_printable(char c)
+{
+    return c >= ' ' && c <= '~';
+}
+
+bool is_graphic(char c)
+{
+    return c > ' ' && c <= '~';
+}
+
+bool is_alpha(char c)
+{
+    return is_lowercase(c) || is_uppercase(c);
+}
+
+bool is_alphanum(char c)
+{
+    return is_alpha(c) || is_digit(c);
+}
+
+bool is_hex_digit(char c)
+{
+    return is_digit(c)
+        || (c >= 'A' && c <= 'F')
+        || (c >= 'a' && c <= 'f');
+}
+
+bool is_quote(char c)
+{
+    return c == '\'' || c == '"';
+}
+
+bool is_path_separator(char c)
+{
+    return c == '/' || c == '\\';
+}
+
+}