more smaller sources, another page in the book

makefile

@@ -5,12 +5,19 @@ CC := clang -c -std=c17 -Wall -Wextra -pedantic -Werror
 SRCS := $(shell find $(SRC) -name '*.c')
 OBJS := $(SRCS:%=$(TARGET)/%.o)
 
-$(TARGET)/lox: $(TARGET)/lox.c.o $(TARGET)/tokens.c.o
+$(TARGET)/lox: $(TARGET)/lox.c.o $(TARGET)/scanner.c.o $(TARGET)/tokens.c.o $(TARGET)/utils.c.o
-	clang $(TARGET)/lox.c.o -L$(TARGET) -ltokens.c.o -o $(TARGET)/lox
+	clang $(TARGET)/lox.c.o -L$(TARGET) -ltokens.c.o -lscanner.c.o -lutils.c.o -o $(TARGET)/lox
+
+$(TARGET)/utils.c.o: $(SRC)/utils.c
+	$(CC) $< -o $@
 
 $(TARGET)/tokens.c.o: $(SRC)/tokens.c
 	$(CC) $< -o $@
 
+$(TARGET)/scanner.c.o: $(SRC)/scanner.c
+	$(CC) $< -o $@
+
+
 $(TARGET)/lox.c.o: $(SRC)/lox.c $(TARGET)
 	$(CC) $< -o $@
 

src/lox.c

@@ -2,18 +2,13 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdbool.h>
+#include "scanner.h"
 #include "tokens.h"
+#include "utils.h"
 
 int run_file(char* file);
 void run_prompt(void);
-void run(char* source);
+ScanResult run(char* source);
-void scan_tokens(char* source);
-void scan_token(char* source, int line, int start, int* current_pos, TokenList* token_list);
-void error(int line, char* nessage);
-void report(int line, char* where, char* message);
-char* substring(char* string, int position, int length);
-
-static bool had_error = false;
 
 int main(int argc, char* argv[]){
     if (argc>2){
@@ -27,8 +22,8 @@ int main(int argc, char* argv[]){
     return EXIT_SUCCESS;
 }
 
-
 int run_file(char* filename){
+
     FILE* file = fopen(filename, "r");
     if (file == NULL){
         printf("unable to open file '%s'\n", filename);
@@ -54,15 +49,17 @@ int run_file(char* filename){
 
     fclose(file);
 
-    run(content);
+    ScanResult scan_result = run(content);
 
     // FREE UP
     free(content);
 
-    if (had_error){
+    if (scan_result.had_error){
         return 65;
     }
 
+    tokenlist_print(&scan_result.token_list);
+
     return EXIT_SUCCESS;
 }
 
@@ -78,86 +75,12 @@ void run_prompt(void){
         }
 
         int len =(int)strlen(line);
-        run(substring(line, 1, len-1));
+        ScanResult scan_result = run(substring(line, 1, len-1));
-        had_error = false;
+
+        tokenlist_print(&scan_result.token_list);
     }
 }
 
-void run(char* source){
+ScanResult run(char* source){
-    scan_tokens(source);
+    return scan_tokens(source);
-}
-
-void scan_tokens(char* source){
-    int current = 0;
-    int start = 0;
-    int line = 1;
-
-    TokenList token_list;
-    tokenlist_init(&token_list);
-    int len = (int)strlen(source);
-
-    while (current < len) {
-        start = current;
-        scan_token(source, line, start, &current, &token_list);
-    }
-    tokenlist_print(&token_list);
-}
-
-void add_token(char* source, int line, TokenList* token_list, enum TokenType type, int start, int current_pos){
-    Token token;
-    token.type = type;
-    token.lexeme = substring(source, start, current_pos);
-    token.literal = NULL;
-    token.line = line;
-
-    tokenlist_add(token_list, token);
-}
-
-char advance(char * source, int* pos){
-    char c = source[*pos];
-    (*pos) +=1;
-    return c;
-}
-
-void scan_token(char* source, int line, int start, int* current_pos, TokenList* token_list){
-    char c = advance(source, current_pos);
-
-    switch (c){
-        case '(': add_token(source, line, token_list, LEFT_PAREN, start, *current_pos); break;
-        case ')': add_token(source, line, token_list, RIGHT_PAREN, start, *current_pos); break;
-        case '{': add_token(source, line, token_list, LEFT_BRACE, start, *current_pos); break;
-        case '}': add_token(source, line, token_list, RIGHT_BRACE, start, *current_pos); break;
-        case ',': add_token(source, line, token_list, COMMA, start, *current_pos); break;
-        case '.': add_token(source, line, token_list, DOT, start, *current_pos); break;
-        case '+': add_token(source, line, token_list, PLUS, start, *current_pos); break;
-        case '-': add_token(source, line, token_list, MINUS, start, *current_pos); break;
-
-        default: error(line, "Unexpected character."); break;
-    }
-}
-
-void error(int line, char* message){
-    report(line, "", message);
-}
-
-void report(int line, char* where, char* message){
-    printf("*[Line %i] Error %s : %s\n", line, where, message);
-    had_error = true;
-}
-
-char* substring(char* string, int position, int length){
-    char* ptr = malloc(length+1);
-    if (ptr == NULL) {
-        printf("out of memory");
-        exit(EXIT_FAILURE);
-    }
-
-    int c;
-    for (c=0; c < length; c+=1){
-        *(ptr+c) = *(string+position-1);
-        string += sizeof(char);
-    }
-    *(ptr+c) = '\0';
-
-    return ptr;
 }

src/scanner.c

@@ -0,0 +1,124 @@
+#include "scanner.h"
+#include "tokens.h"
+#include "utils.h"
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void scan_token(void);
+void error(char *message);
+void report(char *where, char *message);
+bool is_at_end(void);
+bool match(char expected);
+
+bool had_error = false;
+int current_pos = -1;
+int start = -1;
+int current_line = -1;
+char *source;
+TokenList token_list;
+
+ScanResult scan_tokens(char *src) {
+  current_pos = 0;
+  start = 0;
+  current_line = 1;
+  source = src;
+
+  tokenlist_init(&token_list);
+  int len = (int)strlen(source);
+
+  while (current_pos < len) {
+    start = current_pos;
+    scan_token();
+  }
+
+  ScanResult scan_result;
+  scan_result.token_list = token_list;
+  scan_result.had_error = had_error;
+
+  // tokenlist_print(&scan_result.token_list);
+
+  return scan_result;
+}
+
+void add_token(enum TokenType type) {
+  Token token;
+  token.type = type;
+  token.lexeme = substring(source, start, current_pos);
+  token.literal = NULL;
+  token.line = current_line;
+
+  tokenlist_add(&token_list, token);
+}
+
+char advance(void) {
+  char c = source[current_pos++];
+  return c;
+}
+
+void scan_token(void) {
+  char c = advance();
+
+  switch (c) {
+  case '(':
+    add_token(LEFT_PAREN);
+    break;
+  case ')':
+    add_token(RIGHT_PAREN);
+    break;
+  case '{':
+    add_token(LEFT_BRACE);
+    break;
+  case '}':
+    add_token(RIGHT_BRACE);
+    break;
+  case ',':
+    add_token(COMMA);
+    break;
+  case '.':
+    add_token(DOT);
+    break;
+  case '+':
+    add_token(PLUS);
+    break;
+  case '-':
+    add_token(MINUS);
+    break;
+  case '!':
+    add_token(match('=') ? BANG_EQUAL : BANG);
+    break;
+  case '=':
+    add_token(match('=') ? EQUAL_EQUAL : EQUAL);
+    break;
+  case '>':
+    add_token(match('=') ? GREATER_EQUAL : GREATER);
+    break;
+  case '<':
+    add_token(match('=') ? LESS_EQUAL : LESS);
+    break;
+  default:
+    error("Unexpected character.");
+    break;
+  }
+}
+
+bool match(char expected) {
+  if (is_at_end()) {
+    return false;
+  }
+  if (expected != source[current_pos]) {
+    return false;
+  }
+  current_pos += 1;
+  return true;
+}
+
+bool is_at_end(void) { return current_pos >= (int)strlen(source); }
+
+void error(char *message) { report("", message); }
+
+void report(char *where, char *message) {
+  printf("*[Line %i] Error %s : %s\n", current_line, where, message);
+  had_error = true;
+}

src/scanner.h

@@ -0,0 +1,14 @@
+#ifndef SCANNER_H
+#define SCANNER_H
+
+#include <stdbool.h>
+#include "tokens.h"
+
+typedef struct {
+    bool had_error;
+    TokenList token_list;
+} ScanResult;
+
+ScanResult scan_tokens(char* source);
+
+#endif

src/utils.c

@@ -0,0 +1,19 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+char* substring(char* string, int position, int length){
+    char* ptr = malloc(length+1);
+    if (ptr == NULL) {
+        printf("out of memory");
+        exit(EXIT_FAILURE);
+    }
+
+    int c;
+    for (c=0; c < length; c+=1){
+        *(ptr+c) = *(string+position-1);
+        string += sizeof(char);
+    }
+    *(ptr+c) = '\0';
+
+    return ptr;
+}

src/utils.h

@@ -0,0 +1,6 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+char* substring(char* string, int position, int length);
+
+#endif