common/chat: add specialized minimax m3 parser (#26210)

common/chat-peg-parser.cpp

@@ -1056,3 +1056,141 @@ void common_chat_peg_gemma4_mapper::visit(const common_peg_ast_arena & arena, co
         visit(arena, child_id);
     }
 }
+
+static void minimax_m3_collect(const common_peg_ast_arena &     arena,
+                               const common_peg_ast_node &      node,
+                               const std::string &              tag,
+                               std::vector<common_peg_ast_id> & out) {
+    for (auto child_id : node.children) {
+        const auto & child = arena.get(child_id);
+        if (child.tag == tag) {
+            out.push_back(child_id);
+        } else {
+            minimax_m3_collect(arena, child, tag, out);
+        }
+    }
+}
+
+static common_peg_ast_id minimax_m3_value_of(const common_peg_ast_arena & arena, const common_peg_ast_node & node) {
+    for (auto child_id : node.children) {
+        const auto & tag = arena.get(child_id).tag;
+        if (tag == common_chat_peg_builder::TOOL_ARG_VALUE ||
+            tag == common_chat_peg_builder::TOOL_ARG_STRING_VALUE ||
+            tag == common_chat_peg_minimax_m3_mapper::TOOL_ARG_OBJECT ||
+            tag == common_chat_peg_minimax_m3_mapper::TOOL_ARG_ARRAY) {
+            return child_id;
+        }
+    }
+    return COMMON_PEG_INVALID_AST_ID;
+}
+
+static std::string minimax_m3_value_to_json(const common_peg_ast_arena & arena, common_peg_ast_id id, bool closed);
+
+static std::string minimax_m3_member_to_json(const common_peg_ast_arena & arena, const common_peg_ast_node & node) {
+    auto name_id = arena.find_by_tag(node, common_chat_peg_builder::TOOL_ARG_NAME);
+    if (name_id == COMMON_PEG_INVALID_AST_ID) {
+        return "";
+    }
+
+    return ordered_json(arena.get(name_id).text).dump() + ":" +
+           minimax_m3_value_to_json(arena, minimax_m3_value_of(arena, node), !node.is_partial);
+}
+
+static std::string minimax_m3_container_to_json(const common_peg_ast_arena & arena,
+                                                const common_peg_ast_node & node,
+                                                bool                        is_object,
+                                                bool                        closed) {
+    const std::string tag = is_object ? common_chat_peg_builder::TOOL_ARG
+                                      : common_chat_peg_minimax_m3_mapper::TOOL_ARG_ITEM;
+
+    std::vector<common_peg_ast_id> entries;
+    minimax_m3_collect(arena, node, tag, entries);
+
+    std::string result = is_object ? "{" : "[";
+
+    bool add_comma = false;
+    for (auto entry_id : entries) {
+        const auto & entry = arena.get(entry_id);
+
+        std::string text;
+        if (is_object) {
+            text = minimax_m3_member_to_json(arena, entry);
+        } else {
+            text = minimax_m3_value_to_json(arena, minimax_m3_value_of(arena, entry), !entry.is_partial);
+        }
+
+        if (text.empty()) {
+            continue;
+        }
+
+        if (add_comma) {
+            result += ",";
+        }
+        add_comma = true;
+        result += text;
+    }
+
+    if (closed) {
+        result += is_object ? "}" : "]";
+    }
+    return result;
+}
+
+static std::string minimax_m3_value_to_json(const common_peg_ast_arena & arena, common_peg_ast_id id, bool closed) {
+    if (id == COMMON_PEG_INVALID_AST_ID) {
+        return "";
+    }
+
+    const auto & node = arena.get(id);
+
+    if (node.tag == common_chat_peg_minimax_m3_mapper::TOOL_ARG_OBJECT) {
+        return minimax_m3_container_to_json(arena, node, /* is_object = */ true, closed);
+    }
+
+    if (node.tag == common_chat_peg_minimax_m3_mapper::TOOL_ARG_ARRAY) {
+        return minimax_m3_container_to_json(arena, node, /* is_object = */ false, closed);
+    }
+
+    if (node.tag == common_chat_peg_builder::TOOL_ARG_STRING_VALUE) {
+        return "\"" + escape_json_string_inner(std::string(node.text)) + (closed ? "\"" : "");
+    }
+
+    // Numbers and booleans are written verbatim by the template
+    return std::string(node.text);
+}
+
+void common_chat_peg_minimax_m3_mapper::from_ast(const common_peg_ast_arena &    arena,
+                                                 const common_peg_parse_result & result) {
+    for (const auto & node : result.nodes) {
+        visit(arena, node);
+    }
+}
+
+void common_chat_peg_minimax_m3_mapper::visit(const common_peg_ast_arena & arena, common_peg_ast_id id) {
+    const auto & node = arena.get(id);
+
+    if (node.tag == common_chat_peg_builder::REASONING) {
+        result.reasoning_content += std::string(node.text);
+        return;
+    }
+
+    if (node.tag == common_chat_peg_builder::CONTENT) {
+        result.content += std::string(node.text);
+        return;
+    }
+
+    if (node.tag == common_chat_peg_builder::TOOL) {
+        auto name_id = arena.find_by_tag(node, common_chat_peg_builder::TOOL_NAME);
+        if (name_id != COMMON_PEG_INVALID_AST_ID) {
+            common_chat_tool_call call;
+            call.name      = std::string(arena.get(name_id).text);
+            call.arguments = minimax_m3_container_to_json(arena, node, /* is_object = */ true, !node.is_partial);
+            result.tool_calls.push_back(call);
+        }
+        return;
+    }
+
+    for (auto child_id : node.children) {
+        visit(arena, child_id);
+    }
+}