diff --git a/include/document.h b/include/document.h
new file mode 100644
index 00000000..c1077096
--- /dev/null
+++ b/include/document.h
@@ -0,0 +1,21 @@
+#ifndef __tree_sitter_document_h__
+#define __tree_sitter_document_h__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdlib.h>
+
+typedef size_t TSSymbol;
+
+typedef struct {
+} TSTree;
+    
+TSTree TSTreeMake();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/include/parser.h b/include/parser.h
new file mode 100644
index 00000000..ea8e08da
--- /dev/null
+++ b/include/parser.h
@@ -0,0 +1,104 @@
+#ifndef __tree_sitter_parser_h__
+#define __tree_sitter_parser_h__
+
+#include "document.h"
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef int TSState;
+typedef struct {
+    TSState state;
+    TSSymbol symbol;
+} TSStackEntry;
+
+typedef struct {
+    TSTree tree;
+    const char *input;
+    size_t position;
+    TSSymbol lookahead_sym;
+    TSState lex_state;
+    TSStackEntry *stack;
+    size_t stack_size;
+} TSParser;
+
+TSParser TSParserMake(const char *input);
+void TSParserShift(TSParser *parser, TSState state);
+void TSParserReduce(TSParser *parser, TSSymbol symbol, int child_count);
+void TSParserError(TSParser *parser);
+void TSParserAdvance(TSParser *parser, TSState lex_state);
+TSState TSParserParseState(const TSParser *parser);
+TSState TSParserLexState(const TSParser *parser);
+void TSParserSetLexState(TSParser *parser, TSState state);
+char TSParserLookaheadChar(const TSParser *parser);
+TSSymbol TSParserLookaheadSym(const TSParser *parser);
+void TSParserSetLookaheadSym(TSParser *parser, TSSymbol symbol);
+
+#pragma mark - DSL
+
+#define START_PARSER() \
+TSParser p = TSParserMake(input),  *parser = &p; \
+next_state: \
+printf("parse state: %d, lookahead: %s\n", PARSE_STATE(), LOOKAHEAD_SYM_NAME());
+    
+#define LOOKAHEAD_SYM_NAME() \
+ts_symbol_names[LOOKAHEAD_SYM()]
+
+#define START_LEXER() \
+if (parser->lookahead_sym > 0) return; \
+next_state: \
+printf("lex state: %d, lookahead: %c\n", LEX_STATE(), LOOKAHEAD_CHAR()); \
+if (LOOKAHEAD_CHAR() == '\0') { \
+  ACCEPT_TOKEN(ts_symbol___END__); \
+} \
+
+#define LOOKAHEAD_SYM() \
+TSParserLookaheadSym(parser)
+
+#define LOOKAHEAD_CHAR() \
+TSParserLookaheadChar(parser)
+
+#define PARSE_STATE() \
+TSParserParseState(parser)
+
+#define LEX_STATE() \
+TSParserLexState(parser)
+
+#define SHIFT(state) \
+{ TSParserShift(parser, state); goto next_state; }
+
+#define SET_LEX_STATE(state_index) \
+{ TSParserSetLexState(parser, state_index); ts_lex(parser); }
+
+#define ADVANCE(state_index) \
+{ TSParserAdvance(parser, state_index); goto next_state; }
+
+#define ACCEPT_INPUT() \
+{ goto done; }
+
+#define ACCEPT_TOKEN(symbol) \
+{ TSParserSetLookaheadSym(parser, symbol); goto done; }
+
+#define REDUCE(symbol, child_count) \
+{ TSParserReduce(parser, symbol, child_count); goto next_state; }
+
+#define PARSE_ERROR() \
+{ TSParserError(parser); goto done; }
+
+#define LEX_ERROR() \
+{ TSParserError(parser); goto done; }
+
+#define FINISH_PARSER() \
+done: \
+return parser->tree;
+
+#define FINISH_LEXER() \
+done:
+    
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/include/runtime.h b/include/runtime.h
deleted file mode 100644
index 5ef700fe..00000000
--- a/include/runtime.h
+++ /dev/null
@@ -1,98 +0,0 @@
-#ifndef tree_sitter_runtime_h
-#define tree_sitter_runtime_h
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include <stdlib.h>
-
-#pragma mark - Tree
-
-typedef struct {
-} TSTree;
-    
-TSTree TSTreeMake();
-
-#pragma mark - Parser
-
-typedef size_t TSSymbol;
-typedef int TSState;
-    
-typedef struct {
-    TSTree tree;
-    const char *input;
-    size_t position;
-    TSState *state_stack;
-    TSSymbol *symbol_stack;
-    size_t state_count;
-    size_t symbol_count;
-} TSParser;
-
-TSParser TSParserMake(const char *input);
-void TSParserShift(TSParser *parser, TSState state);
-void TSParserReduce(TSParser *parser, TSSymbol symbol, int child_count);
-void TSParserError(TSParser *parser);
-TSState TSParserParseState(const TSParser *parser);
-TSState TSParserLexState(const TSParser *parser);
-TSSymbol TSParserLookahead(const TSParser *parser);
-void TSParserSetLexState(const TSParser *parser, TSState state);
-
-#pragma mark - DSL
-
-#define START_PARSER() \
-    TSParser parser = TSParserMake(input); \
-    start: \
-    ts_lex(&parser);
-
-#define START_LEXER() \
-    start:
-
-#define LOOKAHEAD_SYM() \
-    TSParserLookahead(&parser)
-
-#define LOOKAHEAD_CHAR() \
-    'a'
-
-#define PARSE_STATE() \
-    TSParserParseState(&parser)
-
-#define LEX_STATE() \
-    TSParserLexState(parser)
-
-#define SHIFT(number) \
-    { TSParserShift(&parser, number); break; }
-
-#define SET_LEX_STATE(state_index) \
-    { TSParserSetLexState(&parser, state_index); }
-
-#define ADVANCE(state_index) \
-    { break; }
-
-#define ACCEPT_INPUT() \
-    { goto done; }
-
-#define ACCEPT_TOKEN(symbol) \
-    { goto done; }
-
-#define REDUCE(symbol, child_count) \
-    { TSParserReduce(&parser, symbol, child_count); break; }
-
-#define PARSE_ERROR() \
-    TSParserError(&parser)
-
-#define LEX_ERROR() \
-    TSParserError(parser)
-
-#define FINISH_PARSER() \
-    done: \
-    return parser.tree;
-
-#define FINISH_LEXER() \
-    done:
-
-#endif
-    
-#ifdef __cplusplus
-}
-#endif
diff --git a/spec/fixtures/parsers/arithmetic.c b/spec/fixtures/parsers/arithmetic.c
index a600c694..dced0afc 100644
--- a/spec/fixtures/parsers/arithmetic.c
+++ b/spec/fixtures/parsers/arithmetic.c
@@ -1,7 +1,7 @@
-#include "runtime.h"
+#include "parser.h"
 #include <ctype.h>
 
-typedef enum {
+enum ts_symbol {
     ts_symbol_expression,
     ts_symbol_term,
     ts_symbol_factor,
@@ -12,7 +12,20 @@ typedef enum {
     ts_symbol_number,
     ts_symbol_variable,
     ts_symbol___END__
-} ts_symbol;
+};
+
+static const char *ts_symbol_names[] = {
+    "expression",
+    "term",
+    "factor",
+    "4",
+    "3",
+    "1",
+    "2",
+    "number",
+    "variable",
+    "__END__"
+};
 
 static void ts_lex(TSParser *parser) {
     START_LEXER();
diff --git a/src/compiler/code_gen/c_code.cpp b/src/compiler/code_gen/c_code.cpp
index 00699422..31c52a6a 100644
--- a/src/compiler/code_gen/c_code.cpp
+++ b/src/compiler/code_gen/c_code.cpp
@@ -22,6 +22,21 @@ namespace tree_sitter {
                 pos += replace.length();
             }
         }
+
+        string join(vector<string> lines, string separator) {
+            string result;
+            bool started = false;
+            for (auto line : lines) {
+                if (started) result += separator;
+                started = true;
+                result += line;
+            }
+            return result;
+        }
+        
+        string join(vector<string> lines) {
+            return join(lines, "\n");
+        }
         
         string indent(string input) {
             string tab = "    ";
@@ -30,24 +45,32 @@ namespace tree_sitter {
         }
         
         string _switch(string condition, string body) {
-            return "switch (" + condition + ") {\n" +
-            indent(body) + "\n"
-            "}";
+            return join({
+                "switch (" + condition + ") {",
+                indent(body),
+                "}"
+            });
         }
         
         string _case(string value, string body) {
-            return "case " + value + ":\n" +
-            indent(body) + "\n";
+            return join({
+                "case " + value + ":",
+                indent(body), ""
+            });
         }
 
         string _default(string body) {
-            return "default:\n" +
-            indent(body);
+            return join({
+                "default:",
+                indent(body)
+            });
         }
         
         string _if(string condition, string body) {
-            return string("if (") + condition + ")\n" +
-            indent(body) + "\n";
+            return join({
+                "if (" + condition + ")",
+                indent(body), ""
+            });
         }
         
         class CCodeGenerator {
@@ -151,44 +174,56 @@ namespace tree_sitter {
             }
             
             string symbol_enum() {
-                string result = "typedef enum {\n";
+                string result = "enum ts_symbol {\n";
                 for (string rule_name : rule_names)
                     result += indent(symbol_id(rule_name)) + ",\n";
                 result += indent(symbol_id(ParseTable::END_OF_INPUT));
-                return result + "\n"
-                "} ts_symbol;";
+                return result + "\n};";
             }
-            
+
+            string rule_names_list() {
+                string result = "static const char *ts_symbol_names[] = {\n";
+                for (string rule_name : rule_names)
+                    result += indent(string("\"") + rule_name) + "\",\n";
+                result += indent(string("\"") + ParseTable::END_OF_INPUT + "\"");
+                return result + "\n};";
+            }
+
             string includes() {
-                return string(
-                    "#include \"runtime.h\"\n"
-                    "#include <ctype.h>");
+                return join({
+                    "#include \"parser.h\"",
+                    "#include <ctype.h>"
+                });
             }
             
             string parse_function() {
-                return 
-                "TSTree ts_parse_arithmetic(const char *input) {\n" +
-                indent("START_PARSER();") + "\n" +
-                indent(switch_on_parse_state()) + "\n" +
-                indent("FINISH_PARSER();") + "\n"
-                "}";
+                return join({
+                    "TSTree ts_parse_arithmetic(const char *input) {",
+                    indent("START_PARSER();"),
+                    indent(switch_on_parse_state()),
+                    indent("FINISH_PARSER();"),
+                    "}"
+                });
             }
 
             string lex_function() {
-                return 
-                "static void ts_lex(TSParser *parser) {\n" +
-                indent("START_LEXER();") + "\n" +
-                indent(switch_on_lex_state()) + "\n" +
-                indent("FINISH_LEXER();") + "\n"
-                "}";
+                return join({
+                    "static void ts_lex(TSParser *parser) {",
+                    indent("START_LEXER();"),
+                    indent(switch_on_lex_state()),
+                    indent("FINISH_LEXER();"),
+                    "}"
+                });
             }
             
             string code() {
-                return
-                includes() + "\n\n" +
-                symbol_enum() + "\n\n" +
-                lex_function() + "\n\n" +
-                parse_function() + "\n";
+                return join({
+                    includes(),
+                    symbol_enum(),
+                    rule_names_list(),
+                    lex_function(),
+                    parse_function()
+                }, "\n\n") + "\n";
             }
         };
         
diff --git a/src/runtime/parser.c b/src/runtime/parser.c
index 87adda57..d3f06c8d 100644
--- a/src/runtime/parser.c
+++ b/src/runtime/parser.c
@@ -1,49 +1,63 @@
-#include "runtime.h"
-
-
-static int INITIAL_STATE_STACK_SIZE = 100;
-static int INITIAL_SYMBOL_STACK_SIZE = 100;
+#include "parser.h"
+#include <stdio.h>
 
+static int INITIAL_STACK_SIZE = 100;
 
 TSParser TSParserMake(const char *input) {
-    TSState *state_stack = calloc(INITIAL_STATE_STACK_SIZE, sizeof(*state_stack));
-    TSSymbol *symbol_stack = calloc(INITIAL_SYMBOL_STACK_SIZE, sizeof(*symbol_stack));
     TSParser result = {
-        .input = input,
         .tree = TSTreeMake(),
+        .input = input,
         .position = 0,
-        .state_stack = state_stack,
-        .symbol_stack = symbol_stack,
-        .state_count = 0,
-        .symbol_count = 0
+        .lookahead_sym = 0,
+        .lex_state = 0,
+        .stack = calloc(INITIAL_STACK_SIZE, sizeof(TSStackEntry)),
+        .stack_size = 0,
     };
     return result;
 }
 
-void TSParserShift(TSParser *parser, TSState state) {
-    
+void TSParserShift(TSParser *parser, TSState parse_state) {
+    TSStackEntry *entry = (parser->stack + parser->stack_size);
+    entry->state = parse_state;
+    entry->symbol = parser->lookahead_sym;
+    parser->lookahead_sym = -1;
+    parser->stack_size++;
 }
 
 void TSParserReduce(TSParser *parser, TSSymbol symbol, int child_count) {
-    
+    parser->lookahead_sym = symbol;
+    parser->stack_size -= child_count;
 }
 
 void TSParserError(TSParser *parser) {
     
 }
 
-TSSymbol TSParserLookahead(const TSParser *parser) {
-    return 1;
+void TSParserAdvance(TSParser *parser, TSState lex_state) {
+    parser->position++;
+    parser->lex_state = lex_state;
+}
+
+char TSParserLookaheadChar(const TSParser *parser) {
+    return parser->input[parser->position];
+}
+
+TSSymbol TSParserLookaheadSym(const TSParser *parser) {
+    return parser->lookahead_sym;
+}
+
+void TSParserSetLookaheadSym(TSParser *parser, TSSymbol symbol) {
+    parser->lookahead_sym = symbol;
 }
 
 TSState TSParserParseState(const TSParser *parser) {
-    return 5;
+    return parser->stack[parser->stack_size - 1].state;
 }
 
 TSState TSParserLexState(const TSParser *parser) {
-    return 5;
+    return parser->lex_state;
 }
 
-void TSParserSetLexState(const TSParser *parser, TSState lex_state) {
-    
+void TSParserSetLexState(TSParser *parser, TSState lex_state) {
+    parser->lex_state = lex_state;
 }
diff --git a/src/runtime/tree.c b/src/runtime/tree.c
index 1f4a2b5b..469284f1 100644
--- a/src/runtime/tree.c
+++ b/src/runtime/tree.c
@@ -1,9 +1,7 @@
-#include "runtime.h"
-
+#include "document.h"
 
 TSTree TSTreeMake() {
     TSTree result = {
-        
     };
     return result;
 }
\ No newline at end of file
diff --git a/tree_sitter.xcodeproj/project.pbxproj b/tree_sitter.xcodeproj/project.pbxproj
index 19aec9cf..7a0c37d2 100644
--- a/tree_sitter.xcodeproj/project.pbxproj
+++ b/tree_sitter.xcodeproj/project.pbxproj
@@ -109,6 +109,7 @@
 		12130621182C85D300FCF928 /* item_set.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = item_set.h; sourceTree = "<group>"; };
 		121492E9181E200B008E9BDA /* main.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = main.cpp; path = spec/main.cpp; sourceTree = SOURCE_ROOT; };
 		121492EA181E200B008E9BDA /* rules_spec.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = rules_spec.cpp; path = spec/compiler/rules/rules_spec.cpp; sourceTree = SOURCE_ROOT; };
+		121D8B3018795CC0003CF44B /* parser.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = parser.h; sourceTree = "<group>"; };
 		1225CC6318765693000D4723 /* prepare_grammar_spec.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = prepare_grammar_spec.cpp; sourceTree = "<group>"; };
 		1225CC6518765737000D4723 /* prepare_grammar.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = prepare_grammar.cpp; sourceTree = "<group>"; };
 		1225CC6618765737000D4723 /* prepare_grammar.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = prepare_grammar.h; sourceTree = "<group>"; };
@@ -142,7 +143,7 @@
 		12FD4063185E75290041A84E /* generate_parsers.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = generate_parsers.cpp; path = spec/compiler/generate_parsers.cpp; sourceTree = SOURCE_ROOT; };
 		12FD4065185E7C2F0041A84E /* arithmetic.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; name = arithmetic.c; path = spec/fixtures/parsers/arithmetic.c; sourceTree = SOURCE_ROOT; };
 		12FD40D1185EEB5E0041A84E /* runtime_specs */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = runtime_specs; sourceTree = BUILT_PRODUCTS_DIR; };
-		12FD40D4185FED9A0041A84E /* runtime.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = runtime.h; sourceTree = "<group>"; };
+		12FD40D4185FED9A0041A84E /* document.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = document.h; sourceTree = "<group>"; };
 		12FD40DA185FEF0D0041A84E /* arithmetic_spec.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = arithmetic_spec.cpp; sourceTree = "<group>"; };
 		12FD40DC185FF12C0041A84E /* parser.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = parser.c; sourceTree = "<group>"; };
 		12FD40DE1860064C0041A84E /* tree.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = tree.c; sourceTree = "<group>"; };
@@ -390,7 +391,8 @@
 		12FD40D3185FED630041A84E /* include */ = {
 			isa = PBXGroup;
 			children = (
-				12FD40D4185FED9A0041A84E /* runtime.h */,
+				12FD40D4185FED9A0041A84E /* document.h */,
+				121D8B3018795CC0003CF44B /* parser.h */,
 			);
 			path = include;
 			sourceTree = "<group>";