day 2: solution to task 1

day_2/Makefile

@@ -0,0 +1,54 @@
+CC := clang
+YACC := bison
+LEX := flex
+CFLAGS := -std=c17 -Wpedantic -Wall -Wextra
+BUILD := ./build
+INCLUDE	:= -I./
+OBJ_DIR := $(BUILD)/objects
+APP_DIR := $(BUILD)/bin
+TARGET := day_2
+
+SRC := $(wildcard ./*.cpp) lexer.c parser.c
+
+OBJECTS	:= $(SRC:%.c=$(OBJ_DIR)/%.o)
+
+# targets
+all: build $(APP_DIR)/$(TARGET)
+
+run: all
+	$(APP_DIR)/$(TARGET)
+
+flex:
+	$(LEX) --outfile=lexer.c --header-file=lexer.h lexer.l
+
+bison:
+	$(YACC) --output=parser.c parser.y
+
+generate: flex bison
+
+$(OBJ_DIR)/%.o: %.c
+	@mkdir -p $(@D)
+	$(CC) $(CFLAGS) $(INCLUDE) -o $@ -c $<
+
+$(APP_DIR)/$(TARGET): flex bison $(OBJECTS)
+	@mkdir -p $(@D)
+	$(CC) $(CFLAGS) $(INCLUDE) $(LDFLAGS) -o $(APP_DIR)/$(TARGET) $(OBJECTS)
+
+.PHONY: all build clean debug release
+
+build:
+	@mkdir -p $(APP_DIR)
+	@mkdir -p $(OBJ_DIR)
+
+debug: CFLAGS += -DDEBUG -g
+debug: all
+
+sanitize: CFLAGS += -DDEBUG -g -fsanitize=address
+sanitize: all
+
+release: CFLAGS += -O2
+release: all
+
+clean:
+	-@rm -rvf $(BUILD)
+	-@rm -rvf {lexer.c,parser.c} {lexer.h,parser.h}

day_2/lexer.l

@@ -0,0 +1,40 @@
+%{ /* -*- C -*- */
+#include <stdio.h>
+#include <stdlib.h>
+#include "parser.h"
+%}
+
+%option warn nodefault
+
+/* makes the scanner terminate after reaching <<EOF>> instead of assuming a new input was provided */
+%option noyywrap
+/* disable some unused functionality, add scanner tracking */
+%option nounput noinput batch debug
+
+/* gimme a reentrant parser (overkill but more pure) */
+%option reentrant
+
+%option bison-bridge
+
+
+NL      [\n]
+SPACE   [ \t]
+ROCK    [AX]
+PAPER   [BY]
+SCISSOR [CZ]
+
+
+%%
+
+{NL}        { return NEWLINE; }
+{SPACE}+    { /* don't care */}
+{ROCK}      { return ROCK; }
+{PAPER}     { return PAPER; }
+{SCISSOR}   { return SCISSOR; }
+<<EOF>>     { return END_OF_FILE; }
+.           {
+                printf("[error] Encountered unexpected token %s\n", yytext);
+                return 0;
+            }
+
+%%

day_2/parser.y

@@ -0,0 +1,96 @@
+/* Require bison minimal version */
+%require "3.2"
+
+/* write out a header file containing the token defines */
+%header
+
+// Code for the header file generated by bison
+%code requires {
+    typedef void* yyscan_t;
+
+    struct parser_state {
+        unsigned long total_score;
+    };
+}
+
+// Code for the c file
+%{
+    #include <stdio.h>
+    #include <stdlib.h>
+    #include "parser.h"
+    #include "lexer.h"
+
+    void yyerror(struct parser_state* state, yyscan_t scanner, const char* msg) {
+        (void)state;
+        (void)scanner;
+        fprintf(stderr, "\033[93mSyntax Error: %s\033[0m\n", msg);
+    }
+%}
+
+// define a reentrant parser
+%define api.pure
+
+// enable parser tracing and detailed error messages (plus Lookahead Correction)
+%define parse.trace
+%define parse.error detailed
+%define parse.lac full
+
+%lex-param   { yyscan_t scanner }
+%parse-param { struct parser_state* state }
+%parse-param { yyscan_t scanner }
+
+%start input
+%token NEWLINE
+%token ROCK PAPER SCISSOR
+%term END_OF_FILE
+
+/* the format is: them<space>me */
+%%
+
+input
+    : line input
+    | END_OF_FILE       { return 0; }
+    ;
+
+line
+    : game_move NEWLINE
+    ;
+
+game_move
+    : ROCK ROCK         { state->total_score += 1 + 3; }
+    | ROCK PAPER        { state->total_score += 2 + 6; }
+    | ROCK SCISSOR      { state->total_score += 3 + 0; }
+    | PAPER ROCK        { state->total_score += 1 + 0; }
+    | PAPER PAPER       { state->total_score += 2 + 3; }
+    | PAPER SCISSOR     { state->total_score += 3 + 6; }
+    | SCISSOR ROCK      { state->total_score += 1 + 6; }
+    | SCISSOR PAPER     { state->total_score += 2 + 0; }
+    | SCISSOR SCISSOR   { state->total_score += 3 + 3; }
+    ;
+
+%%
+
+int main(void) {
+    struct parser_state parser_state;
+    parser_state.total_score = 0;
+
+    yyscan_t scanner;
+
+    if (yylex_init(&scanner)) {
+        fprintf(stderr, "\033[91m[error] Could not initialize lexer\n");
+        return EXIT_FAILURE;
+    }
+
+    if (yyparse(&parser_state, scanner)) {
+		// TODO: Error handling https://www.gnu.org/software/bison/manual/html_node/Parser-Function.html
+		// error during parse occured
+		return EXIT_FAILURE;
+	}
+
+    yylex_destroy(scanner);
+    
+    // task 2
+    printf("total score: %lu\n", parser_state.total_score);
+
+    return 0;
+}