feat: implement HTML lexer and integrate tokenization into browser output

1 files changed, 121 insertions, 0 deletions

diff --git a/src/parser/html_lexer.cc b/src/parser/html_lexer.cc
new file mode 100644
index 0000000..bbf8c57
--- /dev/null
+++ b/src/parser/html_lexer.cc
@@ -0,0 +1,121 @@
+/*
+ * Ricochet - A minimalist CLI web browser for fast, distraction-free navigation.
+ * Copyright (C) 2026  Richard Qin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "ricochet/parser/html_lexer.hh"
+
+#include <cstdint>
+#include <string_view>
+
+
+namespace ricochet::parser {
+
+namespace {
+enum class LexerState : std::uint8_t {
+    Data,              // Reading plain text
+    TagOpen,           // Just encountered '<'
+    TagName,           // Reading the name of an opening tag (e.g., "div")
+    ClosingTagName,    // Reading the name of a closing tag (e.g., "/div")
+    SwallowAttributes  // Ignore attributes mode (ignore until encountering '>')
+};
+
+void emit_text(std::string& buffer, std::vector<HtmlToken>& tokens) {
+    if (buffer.empty()) {
+        return; // 提前返回，减少 if 嵌套层级
+    }
+
+    bool all_whitespace = true;
+    for (const char c : buffer) {
+        if (!std::isspace(static_cast<unsigned char>(c))) {
+            all_whitespace = false;
+            break;
+        }
+    }
+    
+    if (!all_whitespace) {
+        tokens.emplace_back(TextToken{buffer});
+    }
+    buffer.clear();
+}
+
+} // namespace
+
+std::vector<HtmlToken> HtmlLexer::tokenize( std::string_view html ) const // NOLINT(readability-convert-member-functions-to-static)
+{
+  std::vector<HtmlToken> tokens;
+
+  LexerState state = LexerState::Data;
+  std::string buffer{};
+
+  for (const char c : html) {
+    switch (state) {
+    case LexerState::Data:
+        if (c == '<') {
+            emit_text(buffer, tokens);
+            state = LexerState::TagOpen;
+        } else {
+            buffer += c;
+        }
+        break;
+    case LexerState::TagOpen:
+        if (c == '/') {
+            state = LexerState::ClosingTagName;
+        } else if (std::isalpha(static_cast<unsigned char>(c))) {
+            buffer.push_back(c);
+            state = LexerState::TagName;
+        } else {
+            buffer.push_back('<');
+            buffer.push_back(c);
+            state = LexerState::Data;
+        }
+        break;
+    case LexerState::TagName:
+        if (c == '>') {
+            tokens.emplace_back(TagOpenToken{buffer});
+            buffer.clear();
+            state = LexerState::Data;
+        } else if (std::isspace(static_cast<unsigned char>(c))) {
+            tokens.emplace_back(TagOpenToken{buffer});
+            buffer.clear();
+            state = LexerState::SwallowAttributes;
+        } else {
+            buffer += static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
+        }
+        break;
+    case LexerState::ClosingTagName:
+        if (c == '>') {
+            tokens.emplace_back(TagCloseToken{buffer});
+            buffer.clear();
+            state = LexerState::Data;
+        } else {
+            buffer += static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
+        }
+        break;
+    case LexerState::SwallowAttributes:
+        if (c == '>') {
+            state = LexerState::Data;
+        }
+        break;
+    }
+  }
+
+  emit_text(buffer, tokens);
+
+  return tokens;
+}
+
+} // namespace ricochet::parser
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