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280 lines
7.4 KiB
C++
280 lines
7.4 KiB
C++
/*
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* Copyright (c) 2020, Benoit Lormeau <blormeau@outlook.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/NonnullOwnPtr.h>
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#include <AK/RedBlackTree.h>
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#include <AK/Result.h>
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#include <AK/String.h>
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#include <AK/StringView.h>
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namespace AK {
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class GenericLexer {
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public:
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constexpr explicit GenericLexer(StringView input)
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: m_input(input)
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{
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}
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constexpr size_t tell() const { return m_index; }
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constexpr size_t tell_remaining() const { return m_input.length() - m_index; }
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StringView remaining() const { return m_input.substring_view(m_index); }
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StringView input() const { return m_input; }
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constexpr bool is_eof() const { return m_index >= m_input.length(); }
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constexpr char peek(size_t offset = 0) const
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{
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return (m_index + offset < m_input.length()) ? m_input[m_index + offset] : '\0';
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}
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Optional<StringView> peek_string(size_t length, size_t offset = 0) const
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{
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if (m_index + offset + length > m_input.length())
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return {};
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return m_input.substring_view(m_index + offset, length);
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}
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constexpr bool next_is(char expected) const
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{
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return peek() == expected;
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}
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constexpr bool next_is(StringView expected) const
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{
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for (size_t i = 0; i < expected.length(); ++i)
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if (peek(i) != expected[i])
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return false;
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return true;
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}
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constexpr bool next_is(char const* expected) const
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{
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for (size_t i = 0; expected[i] != '\0'; ++i)
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if (peek(i) != expected[i])
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return false;
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return true;
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}
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constexpr void retreat()
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{
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VERIFY(m_index > 0);
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--m_index;
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}
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constexpr void retreat(size_t count)
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{
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VERIFY(m_index >= count);
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m_index -= count;
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}
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constexpr char consume()
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{
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VERIFY(!is_eof());
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return m_input[m_index++];
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}
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template<typename T>
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constexpr bool consume_specific(T const& next)
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{
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if (!next_is(next))
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return false;
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if constexpr (requires { next.length(); }) {
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ignore(next.length());
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} else {
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ignore(sizeof(next));
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}
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return true;
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}
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bool consume_specific(ByteString next) = delete;
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bool consume_specific(String const& next)
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{
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return consume_specific(next.bytes_as_string_view());
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}
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constexpr bool consume_specific(char const* next)
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{
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return consume_specific(StringView { next, __builtin_strlen(next) });
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}
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constexpr char consume_escaped_character(char escape_char = '\\', StringView escape_map = "n\nr\rt\tb\bf\f"sv)
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{
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if (!consume_specific(escape_char))
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return consume();
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auto c = consume();
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for (size_t i = 0; i < escape_map.length(); i += 2) {
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if (c == escape_map[i])
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return escape_map[i + 1];
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}
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return c;
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}
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StringView consume(size_t count);
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StringView consume_all();
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StringView consume_line();
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StringView consume_until(char);
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StringView consume_until(char const*);
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StringView consume_until(StringView);
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StringView consume_quoted_string(char escape_char = 0);
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Optional<ByteString> consume_and_unescape_string(char escape_char = '\\');
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template<Integral T>
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ErrorOr<T> consume_decimal_integer();
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enum class UnicodeEscapeError {
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MalformedUnicodeEscape,
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UnicodeEscapeOverflow,
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};
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Result<u32, UnicodeEscapeError> consume_escaped_code_point(bool combine_surrogate_pairs = true);
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constexpr void ignore(size_t count = 1)
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{
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count = min(count, m_input.length() - m_index);
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m_index += count;
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}
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constexpr void ignore_until(char stop)
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{
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while (!is_eof() && peek() != stop) {
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++m_index;
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}
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}
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constexpr void ignore_until(char const* stop)
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{
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while (!is_eof() && !next_is(stop)) {
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++m_index;
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}
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}
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/*
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* Conditions are used to match arbitrary characters. You can use lambdas,
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* ctype functions, or is_any_of() and its derivatives (see below).
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* A few examples:
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* - `if (lexer.next_is(isdigit))`
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* - `auto name = lexer.consume_while([](char c) { return isalnum(c) || c == '_'; });`
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* - `lexer.ignore_until(is_any_of("<^>"));`
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*/
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// Test the next character against a Condition
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template<typename TPredicate>
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constexpr bool next_is(TPredicate pred) const
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{
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return pred(peek());
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}
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// Consume and return characters while `pred` returns true
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template<typename TPredicate>
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StringView consume_while(TPredicate pred)
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{
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size_t start = m_index;
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while (!is_eof() && pred(peek()))
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++m_index;
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size_t length = m_index - start;
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return m_input.substring_view(start, length);
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}
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// Consume and return characters until `pred` return true
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template<typename TPredicate>
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StringView consume_until(TPredicate pred)
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{
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size_t start = m_index;
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while (!is_eof() && !pred(peek()))
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++m_index;
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size_t length = m_index - start;
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return m_input.substring_view(start, length);
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}
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// Ignore characters while `pred` returns true
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template<typename TPredicate>
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constexpr void ignore_while(TPredicate pred)
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{
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while (!is_eof() && pred(peek()))
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++m_index;
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}
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// Ignore characters until `pred` returns true
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template<typename TPredicate>
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constexpr void ignore_until(TPredicate pred)
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{
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while (!is_eof() && !pred(peek()))
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++m_index;
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}
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protected:
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Result<u32, UnicodeEscapeError> decode_code_point();
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Result<u32, UnicodeEscapeError> decode_single_or_paired_surrogate(bool combine_surrogate_pairs = true);
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StringView m_input;
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size_t m_index { 0 };
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};
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class LineTrackingLexer : public GenericLexer {
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public:
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struct Position {
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size_t offset { 0 };
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size_t line { 0 };
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size_t column { 0 };
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};
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LineTrackingLexer(StringView input, Position start_position)
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: GenericLexer(input)
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, m_first_line_start_position(start_position)
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, m_line_start_positions(make<RedBlackTree<size_t, size_t>>())
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{
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m_line_start_positions->insert(0, 0);
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auto first_newline = input.find('\n').map([](auto x) { return x + 1; }).value_or(input.length());
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m_line_start_positions->insert(first_newline, 1);
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m_largest_known_line_start_position = first_newline;
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}
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LineTrackingLexer(StringView input)
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: LineTrackingLexer(input, { 0, 1, 1 })
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{
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}
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Position position_for(size_t) const;
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Position current_position() const { return position_for(m_index); }
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protected:
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Position m_first_line_start_position;
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mutable NonnullOwnPtr<RedBlackTree<size_t, size_t>> m_line_start_positions; // offset -> line index
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mutable size_t m_largest_known_line_start_position { 0 };
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};
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constexpr auto is_any_of(StringView values)
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{
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return [values](auto c) { return values.contains(c); };
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}
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constexpr auto is_not_any_of(StringView values)
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{
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return [values](auto c) { return !values.contains(c); };
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}
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constexpr auto is_path_separator = is_any_of("/\\"sv);
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constexpr auto is_quote = is_any_of("'\""sv);
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}
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#if USING_AK_GLOBALLY
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using AK::GenericLexer;
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using AK::is_any_of;
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using AK::is_path_separator;
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using AK::is_quote;
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using AK::LineTrackingLexer;
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#endif
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