wip parser structure with placeholders

src/parser.c

@@ -1,10 +1,109 @@
 #include "parser.h"
 
+/**
+    TOKEN_VARIABLE,      // x, y, etc.
+    TOKEN_NUMBER_INT,    // int
+    TOKEN_NUMBER_DOUBLE, // double
+    TOKEN_POWER,         // ^ or **
+    TOKEN_SIGN,          // + or -
+    TOKEN_FACTOR,        // * or /
+    TOKEN_EQUAL,         // =
+    TOKEN_END            // null (end of input)
+
+    1. VARIABLE | NUMBER_INT | NUMBER_DOUBLE | POWER | SIGN | FACTOR | EQUAL | END
+    2. VARIABLE | NUMBER_INT | NUMBER_DOUBLE | POWER | SIGN | FACTOR | EQUAL | END
+    3. VARIABLE | NUMBER_INT | NUMBER_DOUBLE | POWER | SIGN | FACTOR | EQUAL | END
+
+    term_position position;
+    term_sign sign;
+    coefficient_type coefficient_type;
+    union
+    {
+        int coefficient_int;
+        double coefficient_double;
+    };
+    int exponent;
+ */
+
+static term_sign get_sign(token *tokens, int *token_count)
+{
+    if (tokens)           // placeholder
+        *token_count = 1; // placeholder
+    return '+';           // placeholder
+}
+
+static void get_coefficient(token *tokens, int *token_count, coefficient_type *coefficient_type, int *coefficient_int, double *coefficient_double)
+{
+    if (tokens && coefficient_type && coefficient_double && coefficient_int) // placeholder
+        *token_count = 1;                                                    // placeholder
+}
+
+static int get_exponent(token *tokens, int *token_count)
+{
+    if (tokens)           // placeholder
+        *token_count = 1; // placeholder
+    return 1;             // placeholder
+}
+
 int parse(token *tokens, term *terms)
 {
+    /*
     if (tokens)
     {
-        terms[0].type = 0;
+        terms[0].exponent = 0;
     }
     return 1;
+    */
+
+    int i;
+    int term_count;
+    int token_count;
+    int coefficient_int;
+    double coefficient_double;
+    term_position term_position;
+    coefficient_type coefficient_type;
+
+    term_count = 0;
+    token_count = 0;
+    i = 0;
+    term_position = TERM_LEFT;
+    while (tokens[i].type != TOKEN_END)
+    {
+        coefficient_int = 0;
+        coefficient_double = 0.0;
+
+        if (tokens[i].type == TOKEN_EQUAL)
+        {
+            term_position = TERM_RIGHT;
+            i++;
+            break;
+        }
+
+        // position
+        terms[term_count].position = term_position;
+
+        // sign
+        terms[term_count].sign = get_sign(&tokens[i], &token_count);
+        i += token_count;
+
+        // coefficient
+        get_coefficient(&tokens[i], &token_count, &coefficient_type, &coefficient_int, &coefficient_double);
+        if (coefficient_type == TYPE_INT)
+        {
+            terms[term_count].coefficient_int = coefficient_int;
+        }
+        else if (coefficient_type == TYPE_DOUBLE)
+        {
+            terms[term_count].coefficient_double = coefficient_double;
+        }
+        i += token_count;
+
+        // exponent
+        terms[term_count].exponent = get_exponent(&tokens[i], &token_count);
+        i += token_count;
+
+        i++;
+    }
+
+    return term_count;
 }