From ecc12f6f3b3039ede67e05e24e837a2392eebb42 Mon Sep 17 00:00:00 2001
From: Jacob Signorovitch <jacob.signorovitch@gmail.com>
Date: Sat, 2 Nov 2024 10:31:55 -0400
Subject: [PATCH] Begin bison-based parsing.

---
 .gitignore          |  1 +
 Makefile            | 13 ++++++++++++-
 src/grammar.y       | 17 +++++++++++++++++
 src/include/lexer.h |  3 +++
 src/lexer.c         |  4 ++++
 5 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 src/grammar.y

diff --git a/.gitignore b/.gitignore
index 16b9a79..57274f2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,4 +3,5 @@
 tags
 *.out
 .cache
+build/*
 compile_commands.json
diff --git a/Makefile b/Makefile
index bc39823..cafa0f1 100644
--- a/Makefile
+++ b/Makefile
@@ -3,8 +3,10 @@ NAME = scl
 TARGET = $(NAME).out
 
 SRC_DIR = src
+INC_DIR = $(SRC_DIR)/include
 BUILD_DIR = build
 OBJ_DIR = $(BUILD_DIR)/obj
+GRAM_DIR = $(BUILD_DIR)/grammars
 TEST_DIR = test
 TEST_BUILD_DIR = $(BUILD_DIR)/test
 TEST_OBJ_DIR = $(TEST_BUILD_DIR)/obj
@@ -36,13 +38,22 @@ run: $(TARGET)
 	@ echo -e "$(WHITE_BOLD)Running... $(RESETCOLOR)./$(TARGET)"
 	@ ./$(TARGET)
 
+# Generate grammars with bison.
+grammars: $(SRC_DIR)/grammar.y
+	@ mkdir -p $(GRAM_DIR)
+	@ echo -e "$(WHITE_BOLD)Generating grammars...$(RESETCOLOR) bison $< -o$(GRAM_DIR)/grammar.tab.c -H$(GRAM_DIR)/grammar.tab.h"
+	@ bison $< -o$(GRAM_DIR)/grammar.tab.c -H$(GRAM_DIR)/grammar.tab.h
+
 # Link to final binary.
 $(TARGET): $(OBJ_FILES)
 	@ echo -e "$(WHITE_BOLD)Linking $(WHITE)$(TARGET)$(WHITE_BOLD)...$(RESETCOLOR) $(CC) -o $(TARGET) $(OBJ_FILES) $(LDFLAGS)"
 	@ $(LINK) -o $(TARGET) $(OBJ_FILES) $(LDFLAGS)
 
+# Lexer depends on grammars.
+$(OBJ_DIR)/lexer.o: grammars
+
 # Compile project sources.
-$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c $(SRC_DIR)/include/%.h
+$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c $(INC_DIR)/%.h
 	@ mkdir -p $(OBJ_DIR)
 	@ echo -e "$(WHITE_BOLD)Compiling $(WHITE)$<$(WHITE_BOLD)... $(RESETCOLOR)$(CC) $(CFLAGS) -c $< -o $@"
 	@ $(CC) $(CFLAGS) -c $< -o $@
diff --git a/src/grammar.y b/src/grammar.y
new file mode 100644
index 0000000..4025133
--- /dev/null
+++ b/src/grammar.y
@@ -0,0 +1,17 @@
+%union {
+    int intval;
+    char* strval;
+}
+
+%token <intval> NUM
+%token <strval> CALL
+%token PLUS
+
+%%
+
+exp:
+   NUM {}
+   | exp PLUS exp {}
+   ;
+
+%%
diff --git a/src/include/lexer.h b/src/include/lexer.h
index abfc94f..fc0ca20 100644
--- a/src/include/lexer.h
+++ b/src/include/lexer.h
@@ -68,4 +68,7 @@ void lexer_print_i(Lexer* lexer, int ilvl);
 // Print a representation of a LexerState.
 void lexerstate_print_raw(LexerState s);
 
+// Interface with bison.
+int yylex();
+
 #endif
diff --git a/src/lexer.c b/src/lexer.c
index 680731a..6693afc 100644
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -143,3 +143,7 @@ void lexerstate_print_raw(LexerState s) {
         log_dbgf("%d is not a valid LexerState (max: %d)", s, TOKEN_TYPE_MAX);
     } else printf("%s", lexerstate_names[s]);
 }
+
+int yylex() {
+    lexer_lex()
+}