fix(parser + lexer): interaction -- WIP

src/lexer/lexer.c

@@ -13,16 +13,40 @@
 static char *end_last_token;
 static ssize_t remaining_chars;
 static bool at_beginning = true;
+static struct token *last_token;
+static struct token *current_token;
 
-/* @brief: saves state for the next call the the lexer.
+
+/* @brief: sets the current_token to [tok].
+ *        this function is called by token_peek().
+ */
+static void update_current_token(struct token* tok)
+{
+    current_token = tok;
+}
+
+/* @brief: frees the last token and sets it to [tok].
+ *        Also sets current_token to NULL.
+ *        this function is called by token_pop().
  *
  */
-static void save_state(char *stream, ssize_t i)
+static void update_last_token(struct token* tok)
+{
+    free_token(&last_token);
+    last_token = tok;
+}
+
+/* @brief: saves state for the next call to the the lexer.
+ *        this function is called by token_pop().
+ *
+ */
+static void save_state(char *stream, ssize_t i, struct token *tok)
 {
     remaining_chars -= i;
     end_last_token = stream + i;
     at_beginning = false;
-    return;
+
+    update_last_token(tok);
 }
 
 /* @return: true if a special character from the grammar was found,
@@ -67,7 +91,7 @@ static void set_token_spechar(struct token *tok, char *begin, ssize_t size)
  */
 static void set_token_keyword(struct token *tok, char *begin, ssize_t size)
 {
-    if (tok->type != TOKEN_NULL)
+    if (tok->type != TOKEN_NULL || size == 0)
         return;
     if (strncmp(begin, "if", size) == 0)
     {
@@ -101,7 +125,7 @@ static void set_token_keyword(struct token *tok, char *begin, ssize_t size)
  */
 static void set_token_word(struct token *tok, char *begin, ssize_t size)
 {
-    if (tok->type == TOKEN_NULL)
+    if (tok->type == TOKEN_NULL && size != 0)
     {
         tok->type = TOKEN_WORD;
         tok->data = calloc(size + 1, sizeof(char));
@@ -124,13 +148,14 @@ struct token *new_token(char *begin, ssize_t size)
     return tok;
 }
 
-void free_token(struct token *tok)
+void free_token(struct token **tok)
 {
-    if (tok == NULL)
+    if (tok == NULL || *tok == NULL)
         return;
-    if (tok->data != NULL)
+    if ((*tok)->data != NULL)
-        free(tok->data);
+        free((*tok)->data);
-    free(tok);
+    free(*tok);
+    *tok = NULL;
 }
 
 char *stream_init(void)
@@ -156,6 +181,12 @@ char *stream_init(void)
 
 struct token *peek_token(void)
 {
+    // EOF looping mode
+    if (current_token != NULL && current_token->type == TOKEN_EOF)
+    {
+        return current_token;
+    }
+
     char *stream = stream_init();
 
     ssize_t i = 0;
@@ -175,11 +206,18 @@ struct token *peek_token(void)
         i++;
     }
 
-    return new_token(stream, i);
+    struct token *tok = new_token(stream, i);
+    update_current_token(tok);
+    return tok;
 }
 
 struct token *pop_token(void)
 {
+    if (last_token != NULL && last_token->type == TOKEN_EOF)
+    {
+        free_token(&last_token);
+        return NULL;
+    }
     char *stream = stream_init();
 
     ssize_t i = 0;
@@ -199,7 +237,8 @@ struct token *pop_token(void)
         i++;
     }
 
-    save_state(stream, i);
+    struct token *tok = new_token(stream, i);
+    save_state(stream, i, tok);
 
-    return new_token(stream, i);
+    return tok;
 }

src/lexer/lexer.h

@@ -26,7 +26,8 @@ struct token
 
 /*
  * @brief: returns the next (newly allocated) token without consuming it.
- *         if end of input is reached, returns a token of type TOKEN_EOF.
+ *         if end of input is reached, enters in EOF looping node,
+ *         returning only the same token of type TOKEN_EOF.
  *
  */
 struct token *peek_token(void);
@@ -34,6 +35,10 @@ struct token *peek_token(void);
 /*
  * @brief: returns the next (newly allocated) token and consumes it.
  *         if end of input is reached, returns a token of type TOKEN_EOF.
+ *         It also frees the last token created if there was one.
+ * @warning: if the last returned token was a token EOF, it frees it
+ *          and returns NULL. This means that after peeking a token EOF
+ *          in the parser, there must be EXACTLY ONE call to pop_token().
  *
  */
 struct token *pop_token(void);
@@ -58,7 +63,7 @@ struct token *new_token(char *begin, ssize_t size);
 /* @brief: frees the token given in argument
  *
  */
-void free_token(struct token *tok);
+void free_token(struct token **tok);
 
 /*
  * @brief: checks if the stream used for the last token creation is empty.

src/parser/parser.c

@@ -17,33 +17,39 @@
 
 struct ast *get_ast()
 {
-    struct list *result_list = NULL;
+    // struct list *result_list = NULL;
-    struct ast *current_node = NULL;
+    // struct ast *current_node = NULL;
 
-    struct token *token = peek_token();
+    struct token *token = PEEK_TOKEN();
 
-    while (token != NULL && token->type != TOKEN_EOF)
+    if (token->type == TOKEN_EOF)
     {
-        switch (token->type)
+        token = pop_token();
+        // TODO
+        // return ast END.
+    }
+    else if (token->type == TOKEN_NEWLINE)
     {
-        case TOKEN_WORD:
+        token = pop_token();
+        // TODO
+        // return ast EMPTY.
+    }
+    else // TOKEN WORD
+    {
+        // TODO
+        // call parse_list
             current_node = parse_simple_command();
             result_list = list_append(result_list, current_node);
-            break;
-        default:
-            // Forward
-            token = pop_token();
-            break;
-        }
-        token = peek_token();
     }
 
+    /*
     if (token == NULL)
     {
         puts("Internal error: cannot get the following token");
         puts("Hint: EOF might be missing");
         return NULL;
     }
+    */
 
     struct ast *result = ast_create_list(result_list);
     return result;

src/parser/parser.h

@@ -3,6 +3,24 @@
 
 #include "utils/ast/ast.h"
 
+// === Macros
+
+#define PEEK_TOKEN()                                                           \
+    peek_token();                                                              \
+    if (token == NULL)                                                         \
+    {                                                                          \
+        puts("Internal error: cannot get the following token");                \
+        return NULL;                                                           \
+    }
+
+#define POP_TOKEN()                                                            \
+    pop_token();                                                               \
+    if (token == NULL)                                                         \
+    {                                                                          \
+        puts("Internal error: cannot get the following token");                \
+        return NULL;                                                           \
+    }
+
 /* @brief Builds the AST representation of the next command to execute.
  *
  * @return Returns the AST representation of the next command to execute.

src/parser/parsing_utils.c

@@ -8,24 +8,6 @@
 #include "lexer/lexer.h"
 #include "utils/ast/ast.h"
 
-// === Macros
-
-#define PEEK_TOKEN()                                                           \
-    peek_token();                                                              \
-    if (token == NULL)                                                         \
-    {                                                                          \
-        puts("Internal error: cannot get the following token");                \
-        return NULL;                                                           \
-    }
-
-#define POP_TOKEN()                                                            \
-    pop_token();                                                               \
-    if (token == NULL)                                                         \
-    {                                                                          \
-        puts("Internal error: cannot get the following token");                \
-        return NULL;                                                           \
-    }
-
 // === Static functions
 
 /* Returns true if c is a command terminator, false otherwise
@@ -58,8 +40,9 @@ struct ast *parse_simple_command(void)
 
     while (!isterminator(token))
     {
-        command_elements = list_append(command_elements, token->data);
         token = POP_TOKEN();
+        command_elements = list_append(command_elements, token->data);
+        token = PEEK_TOKEN();
     }
 
     struct ast *result = ast_create_command(command_elements);