diff --git a/highlighter.cpp b/highlighter.cpp
new file mode 100644
index 0000000..aa54ee5
--- /dev/null
+++ b/highlighter.cpp
@@ -0,0 +1,50 @@
+#include "highlighter.h"
+#include <algorithm>
+#include <regex>
+
+std::string Highlighter::highlight_text(
+    const std::string& text,
+    const std::vector<std::string>& keywords,
+    const std::string& pre_tag,
+    const std::string& post_tag
+) {
+    auto spans = find_keyword_positions(text, keywords);
+    std::string result = text;
+    
+    // 从后向前插入标签，避免位置偏移
+    std::sort(spans.begin(), spans.end(),
+        [](const HighlightSpan& a, const HighlightSpan& b) {
+            return a.start > b.start;
+        });
+    
+    for (const auto& span : spans) {
+        result.insert(span.start + span.length, post_tag);
+        result.insert(span.start, pre_tag);
+    }
+    
+    return result;
+}
+
+std::vector<Highlighter::HighlightSpan> Highlighter::find_keyword_positions(
+    const std::string& text,
+    const std::vector<std::string>& keywords
+) {
+    std::vector<HighlightSpan> spans;
+    
+    for (const auto& keyword : keywords) {
+        std::regex word_regex(keyword, std::regex::icase);
+        auto words_begin = std::sregex_iterator(
+            text.begin(), text.end(), word_regex
+        );
+        auto words_end = std::sregex_iterator();
+        
+        for (auto i = words_begin; i != words_end; ++i) {
+            spans.push_back({
+                static_cast<size_t>(i->position()),
+                static_cast<size_t>(i->length())
+            });
+        }
+    }
+    
+    return spans;
+} 
\ No newline at end of file