feat: made the firsts system for parser (not yet populated)

src/parser/grammar.c

@@ -1,30 +1,105 @@
-#define _POSIX_C_SOURCE 200809L
-
 // === Includes
 #include "grammar.h"
 
-#include "../utils/hash_map/hash_map.h"
+#include <stdio.h>
+#include <stdlib.h>
+
 #include "grammar_basic.h"
 
 // === Static variables
 
-static struct hash_map *firsts_map = NULL;
+// rule-indexed array containing firsts
+static struct firsts_list *firsts_map = NULL;
 
 // === Static functions
-static enum token_type first(enum rule r)
+
+/* @brief get the first accepted tokens of a rule
+ *
+ * @arg r the rule
+ * @return the accepted tokens as a firsts_list struct
+ */
+static struct firsts_list *first(enum rule r)
 {
-    // TODO
+    if (firsts_map == NULL || firsts_map[r].tokens == NULL)
-    return TOKEN_NULL;
+    {
+        puts("Internal error: attempted to get the firsts of a rule without "
+             "properly initializing the firsts map");
+        return NULL;
+    }
+
+    return &firsts_map[r];
+}
+
+/* @brief Add a token to a rule's firsts (in firsts_map)
+ *
+ * @arg rule the rule to which add a first
+ * @arg token the token to add to the rule's firsts
+ * @return true on success, false on error
+ */
+static bool add_first(enum rule rule, struct token token)
+{
+    struct firsts_list *item = &firsts_map[rule];
+    if (item->tokens != NULL)
+    {
+        // Check for duplicates
+        for (size_t i = 0; i < item->list_length; i++)
+        {
+            if (item->tokens[i].type == token.type)
+                return true;
+        }
+
+        // Append
+        item->list_length++;
+        item->tokens = realloc(
+            item->tokens, (item->list_length) * sizeof(struct firsts_list));
+    }
+    else
+    {
+        // Create entry
+        item->tokens =
+            calloc(item->list_length + 1, sizeof(struct firsts_list));
+    }
+
+    // Check for alloc error
+    if (item->tokens == NULL)
+    {
+        item->list_length = 0;
+        return false;
+    }
+
+    // Fill
+    item->list_length++;
+    item->tokens[item->list_length - 1] = token;
+
+    return true;
+}
+
+/* @brief initializes the firsts_map static variable (does not populate it)
+ * @return true on success, false on error
+ */
+static bool init_firsts_map(void)
+{
+    firsts_map = calloc(NUMBER_OF_RULES, sizeof(struct firsts_list));
+    if (firsts_map == NULL)
+    {
+        puts("Internal error: couldn't create the firsts_map (is your memory "
+             "full ?)");
+        return false;
+    }
+
+    return true;
 }
 
 // === Functions
 
 bool grammar_init(void)
 {
-    // Create firsts hashmap
+    // Initialize the firsts map
-    // TODO
+    bool success = init_firsts_map();
+    if (success != true)
+        return false;
 
-    // Populate the hashmap
+    // Populate the firsts map
     // TODO
 
     return true;
@@ -32,7 +107,16 @@ bool grammar_init(void)
 
 void grammar_close(void)
 {
-    // TODO free hashmap
+    // Deep free firsts map
+    for (int i = 0; i < NUMBER_OF_RULES; i++)
+    {
+        if (firsts_map[i].tokens != NULL)
+        {
+            free(firsts_map[i].tokens);
+        }
+    }
+    free(firsts_map);
+    firsts_map = NULL;
 }
 
 struct ast *parse_input(struct lexer_context *ctx)

src/parser/grammar.h

@@ -26,7 +26,7 @@
 // === Structures
 
 enum rule {
-   RULE_NULL,
+    RULE_NULL = 0,
     RULE_INPUT,
     RULE_LIST,
     RULE_AND_OR,
@@ -36,7 +36,13 @@ enum rule {
     RULE_SHELL_COMMAND,
     RULE_IF,
     RULE_COMPOUND_LIST,
-   RULE_ELSE_CLAUSE
+    RULE_ELSE_CLAUSE,
+    NUMBER_OF_RULES
+};
+
+struct firsts_list {
+    struct token* tokens; // Heap allocated array
+    size_t list_length;
 };
 
 // === Functions

src/parser/grammar_basic.h

@@ -10,18 +10,24 @@
  *         ends by a newline
  *
  * @code list = and_or { ';' and_or } [ ';' ] ;
+ *
+ * @first first(and_or)
  */
 struct ast *parse_list(struct lexer_context *ctx);
 
 /* @brief Only parses a pipeline rule for the moment
  *
  * @code and_or = pipeline { ( '&&' | '||' ) {'\n'} pipeline } ;
+ *
+ * @first first(pipeline)
  */
 struct ast *parse_and_or(struct lexer_context *ctx);
 
 /* @brief Only parses a command rule for the moment
  *
  * @code pipeline = command ;
+ *
+ * @first first(command)
  */
 struct ast *parse_pipeline(struct lexer_context *ctx);
 
@@ -34,6 +40,7 @@ struct ast *parse_pipeline(struct lexer_context *ctx);
  * @code command = simple_command
  *               | shell_command
  *               ;
+ * @first first(simple_command), first(shell_command)
  */
 struct ast *parse_command(struct lexer_context *ctx);
 
@@ -41,18 +48,24 @@ struct ast *parse_command(struct lexer_context *ctx);
  *        ending by a separator
  *
  * @code simple_command = WORD { element } ;
+ *
+ * @first WORD
  */
 struct ast *parse_simple_command(struct lexer_context *ctx);
 
 /* @brief Only parses if rules for the moment
  *
  * @code shell_command = if_rule ;
+ *
+ * @first first(if_rule)
  */
 struct ast *parse_shell_command(struct lexer_context *ctx);
 
 /* @brief Parses a if rule (condition, then-clause, elif-clause, else-clause)
  *
  * @code if_rule = 'if' compound_list 'then' compound_list [else_clause] 'fi' ;
+ *
+ * @first TOKEN_IF
  */
 struct ast *parse_if_rule(struct lexer_context *ctx);
 
@@ -61,6 +74,8 @@ struct ast *parse_if_rule(struct lexer_context *ctx);
  *
  * @code compound_list = {'\n'} and_or { ( ';' | '\n' ) {'\n'} and_or } [';']
  * {'\n'} ;
+ *
+ * @first TOKEN_NEWLINE, first(and_or)
  */
 struct ast *parse_compound_list(struct lexer_context *ctx);
 
@@ -69,6 +84,8 @@ struct ast *parse_compound_list(struct lexer_context *ctx);
  * @code else_clause = 'else' compound_list
  *                   | 'elif' compound_list 'then' compound_list [else_clause]
  *                   ;
+ *
+ * @first TOKEN_ELSE, TOKEN_ELIF
  */
 struct ast *parse_else_clause(struct lexer_context *ctx);