grammar : add support for std::regex_search() with trigger patterns

common/sampling.cpp

@@ -179,24 +179,30 @@ struct common_sampler * common_sampler_init(const struct llama_model * model, co
 #endif // LLAMA_USE_LLGUIDANCE
     } else {
         std::vector<std::string> trigger_patterns;
-        std::vector<std::string> patterns_anywhere;
         std::vector<llama_token> trigger_tokens;
         for (const auto & trigger : params.grammar_triggers) {
             switch (trigger.type) {
                 case COMMON_GRAMMAR_TRIGGER_TYPE_WORD:
                 {
                     const auto & word = trigger.value;
-                    patterns_anywhere.push_back(regex_escape(word));
+                    trigger_patterns.push_back(regex_escape(word));
                     break;
                 }
                 case COMMON_GRAMMAR_TRIGGER_TYPE_PATTERN:
                 {
-                    patterns_anywhere.push_back(trigger.value);
+                    trigger_patterns.push_back(trigger.value);
                     break;
                 }
                 case COMMON_GRAMMAR_TRIGGER_TYPE_PATTERN_FULL:
                 {
-                    trigger_patterns.push_back(trigger.value);
+                    const auto & pattern = trigger.value;
+                    std::string anchored = "^$";
+                    if (!pattern.empty()) {
+                        anchored = (pattern.front() != '^' ? "^" : "")
+                            + pattern
+                            + (pattern.back() != '$' ? "$" : "");
+                    }
+                    trigger_patterns.push_back(anchored);
                     break;
                 }
                 case COMMON_GRAMMAR_TRIGGER_TYPE_TOKEN:
@@ -210,10 +216,6 @@ struct common_sampler * common_sampler_init(const struct llama_model * model, co
             }
         }
 
-        if (!patterns_anywhere.empty()) {
-            trigger_patterns.push_back("^[\\s\\S]*?(" + string_join(patterns_anywhere, "|") + ")[\\s\\S]*");
-        }
-
         std::vector<const char *> trigger_patterns_c;
         trigger_patterns_c.reserve(trigger_patterns.size());
         for (const auto & regex : trigger_patterns) {

src/llama-grammar.cpp

@@ -369,6 +369,54 @@ static void print_rule(
     fprintf(file, "\n");
 }
 
+//
+// Regex utilities
+//
+static llama_grammar_trigger_pattern llama_grammar_trigger_pattern_compile(const std::string & pattern) {
+    llama_grammar_trigger_pattern_type type = LLAMA_GRAMMAR_TRIGGER_PATTERN_TYPE_SEARCH;
+    if (!pattern.empty() && pattern.front() == '^' && pattern.back() == '$') {
+        // If anchored on both ends, consider it a match
+        type = LLAMA_GRAMMAR_TRIGGER_PATTERN_TYPE_MATCH;
+    }
+    return {type, pattern, std::regex(pattern)};
+}
+
+size_t llama_grammar_trigger_pattern::find(const std::string & input) const {
+    auto find_start_pos = [](const std::smatch & match) {
+        // get from the first matched capturing group to the end of the string
+        size_t start = std::string::npos;
+        for (auto i = 1u; i < match.size(); i++) {
+            if (match.length(i) > 0) {
+                start = match.position(i);
+                break;
+            }
+        }
+        if (start == std::string::npos) {
+            start = match.position(0);
+        }
+        return start;
+    };
+
+    if (type == LLAMA_GRAMMAR_TRIGGER_PATTERN_TYPE_MATCH) {
+        // match against the entire input
+        std::smatch match;
+        if (std::regex_match(input, match, regex)) {
+            return find_start_pos(match);
+        }
+    }
+
+    if (type == LLAMA_GRAMMAR_TRIGGER_PATTERN_TYPE_SEARCH) {
+        // search anywhere
+        std::smatch match;
+        if (std::regex_search(input, match, regex)) {
+            return find_start_pos(match);
+        }
+    }
+
+    return std::string::npos;
+}
+
+
 //
 // implementation
 //
@@ -1192,9 +1240,7 @@ struct llama_grammar * llama_grammar_init_impl(
     }
     for (size_t i = 0; i < num_trigger_patterns; i++) {
         GGML_ASSERT(trigger_patterns != nullptr);
-        auto & trigger = vec_trigger_patterns.emplace_back();
-        trigger.pattern = trigger_patterns[i];
-        trigger.regex = std::regex(trigger.pattern);
+        vec_trigger_patterns.emplace_back(llama_grammar_trigger_pattern_compile(trigger_patterns[i]));
     }
 
     // Important: vec_rules has to be moved here, not copied, because stacks contains
@@ -1312,21 +1358,10 @@ void llama_grammar_accept_impl(struct llama_grammar & grammar, llama_token token
             grammar.trigger_buffer_positions.push_back(std::make_pair(token, position));
             grammar.trigger_buffer += piece;
 
-            std::smatch match;
             for (const auto & trigger_pattern : grammar.trigger_patterns) {
-                if (std::regex_match(grammar.trigger_buffer, match, trigger_pattern.regex)) {
+                auto start = trigger_pattern.find(grammar.trigger_buffer);
+                if (start != std::string::npos) {
                     grammar.awaiting_trigger = false;
-                    // get from the first matched capturing group to the end of the string
-                    size_t start = std::string::npos;
-                    for (auto i = 1u; i < match.size(); i++) {
-                        if (match.length(i) > 0) {
-                            start = match.position(i);
-                            break;
-                        }
-                    }
-                    if (start == std::string::npos) {
-                        start = match.position(0);
-                    }
 
                     // replay tokens that overlap with [start, end)
                     for (const auto & [tok, tok_pos] : grammar.trigger_buffer_positions) {

src/llama-grammar.h

@@ -116,9 +116,17 @@ struct llama_grammar_parser {
     void print(FILE * file);
 };
 
+enum llama_grammar_trigger_pattern_type {
+    LLAMA_GRAMMAR_TRIGGER_PATTERN_TYPE_MATCH       = 0,
+    LLAMA_GRAMMAR_TRIGGER_PATTERN_TYPE_SEARCH      = 1,
+};
+
 struct llama_grammar_trigger_pattern {
+    llama_grammar_trigger_pattern_type type;
     std::string pattern;
     std::regex  regex;
+
+    size_t find(const std::string & input) const;
 };
 
 struct llama_grammar {