jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2020-2021, the SerenityOS developers.
3 * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
4 *
5 * SPDX-License-Identifier: BSD-2-Clause
6 */
7
8#pragma once
9
10#include <AK/Format.h>
11#include <AK/Vector.h>
12#include <LibWeb/CSS/Parser/ComponentValue.h>
13#include <LibWeb/CSS/Parser/Tokenizer.h>
14
15namespace Web::CSS::Parser {
16
17template<typename T>
18class TokenStream {
19public:
20 class StateTransaction {
21 public:
22 explicit StateTransaction(TokenStream<T>& token_stream)
23 : m_token_stream(token_stream)
24 , m_saved_iterator_offset(token_stream.m_iterator_offset)
25 {
26 }
27
28 ~StateTransaction()
29 {
30 if (!m_commit)
31 m_token_stream.m_iterator_offset = m_saved_iterator_offset;
32 }
33
34 StateTransaction create_child() { return StateTransaction(*this); }
35
36 void commit()
37 {
38 m_commit = true;
39 if (m_parent)
40 m_parent->commit();
41 }
42
43 private:
44 explicit StateTransaction(StateTransaction& parent)
45 : m_parent(&parent)
46 , m_token_stream(parent.m_token_stream)
47 , m_saved_iterator_offset(parent.m_token_stream.m_iterator_offset)
48 {
49 }
50
51 StateTransaction* m_parent { nullptr };
52 TokenStream<T>& m_token_stream;
53 int m_saved_iterator_offset { 0 };
54 bool m_commit { false };
55 };
56
57 explicit TokenStream(Vector<T> const& tokens)
58 : m_tokens(tokens)
59 , m_eof(make_eof())
60 {
61 }
62 TokenStream(TokenStream<T> const&) = delete;
63 TokenStream(TokenStream<T>&&) = default;
64
65 bool has_next_token()
66 {
67 return (size_t)(m_iterator_offset + 1) < m_tokens.size();
68 }
69
70 T const& next_token()
71 {
72 if (!has_next_token())
73 return m_eof;
74
75 ++m_iterator_offset;
76
77 return m_tokens.at(m_iterator_offset);
78 }
79
80 T const& peek_token(int offset = 0)
81 {
82 if (!has_next_token())
83 return m_eof;
84
85 return m_tokens.at(m_iterator_offset + offset + 1);
86 }
87
88 T const& current_token()
89 {
90 if ((size_t)m_iterator_offset >= m_tokens.size())
91 return m_eof;
92
93 return m_tokens.at(m_iterator_offset);
94 }
95
96 void reconsume_current_input_token()
97 {
98 if (m_iterator_offset >= 0)
99 --m_iterator_offset;
100 }
101
102 StateTransaction begin_transaction() { return StateTransaction(*this); }
103
104 void skip_whitespace()
105 {
106 while (peek_token().is(Token::Type::Whitespace))
107 next_token();
108 }
109
110 size_t token_count() const { return m_tokens.size(); }
111 size_t remaining_token_count() const { return token_count() - m_iterator_offset - 1; }
112
113 void dump_all_tokens()
114 {
115 dbgln("Dumping all tokens:");
116 for (size_t i = 0; i < m_tokens.size(); ++i) {
117 auto& token = m_tokens[i];
118 if ((i - 1) == (size_t)m_iterator_offset)
119 dbgln("-> {}", token.to_debug_string());
120 else
121 dbgln(" {}", token.to_debug_string());
122 }
123 }
124
125 void copy_state(Badge<Parser>, TokenStream<T> const& other)
126 {
127 m_iterator_offset = other.m_iterator_offset;
128 }
129
130private:
131 Vector<T> const& m_tokens;
132 int m_iterator_offset { -1 };
133
134 T make_eof()
135 {
136 if constexpr (IsSame<T, Token>) {
137 return Tokenizer::create_eof_token();
138 }
139 if constexpr (IsSame<T, ComponentValue>) {
140 return ComponentValue(Tokenizer::create_eof_token());
141 }
142 }
143
144 T m_eof;
145};
146
147}