change API of expression to be consistent with dice API

README.md

@@ -109,20 +109,24 @@ dice_free(d20);
 
 The expression API supports multiple die within one mathematical expression.
 Expressions are parsed using [tinyexpr](https://github.com/codeplea/tinyexpr)
-library.
+library. The API works with objects of the type ``dice_expression_t``, which
+are allocated using ``dice_expression_new``, and must be freed by using
+``dice_expression_free``. Expressions in the format of a C string, can be
+parsed by using ``dice_expression_parse``, and a result can be evaluated
+by using ``dice_expression_roll``.
 
 ```C
 int error = 0;
 char const *expr = "1d20+8+4+3-1";
-dice_expression_t e = dice_expression_parse(expr, &err);
+dice_expression_t e = dice_expression_new();
 int64_t result = 0;
 
-if (e == NULL) {
+if (!dice_expression_parse(e, expr, &err)) {
     fprintf(stderr, "error in expression: \"%s\": at %d\n", expr, err);
     goto fail;
 }
 
-if (!dice_expression_evaluate(e, &result)) {
+if (!dice_expression_roll(e, &result)) {
     goto fail;
 }
 

lib/dice.h

@@ -55,9 +55,11 @@ bool dice_get(dice_t d, dice_option_t opt, ...);
 int64_t dice_roll(dice_t d);
 bool dice_evaluate(dice_t d, dice_result_t **res, size_t *reslen);
 
-dice_expression_t dice_expression_parse(char const *s, int *error);
+dice_expression_t dice_expression_new(void);
 void dice_expression_free(dice_expression_t e);
-bool dice_expression_evaluate(dice_expression_t e, int64_t *result);
+
+bool dice_expression_parse(dice_expression_t d, char const *s, int *error);
+bool dice_expression_roll(dice_expression_t e, int64_t *result);
 bool dice_expression_print(dice_expression_t e);
 
 #endif

lib/diceexpr.c

@@ -729,7 +729,7 @@ void dice_expression_free(dice_expression_t e)
     free(e);
 }
 
-dice_expression_t dice_expression_parse(char const *n, int *error)
+dice_expression_t dice_expression_new(void)
 {
     dice_expression_t e = NULL;
 
@@ -738,16 +738,27 @@ dice_expression_t dice_expression_parse(char const *n, int *error)
         return NULL;
     }
 
-    e->expr = te_compile(n, 0, 0, error);
-    if (e->expr == NULL) {
-        free(e);
-        return NULL;
-    }
+    e->expr = NULL;
 
     return e;
 }
 
-bool dice_expression_evaluate(dice_expression_t e, int64_t *result)
+bool dice_expression_parse(dice_expression_t e, char const *n, int *error)
+{
+    if (e->expr != NULL) {
+        te_free(e->expr);
+        e->expr = NULL;
+    }
+
+    e->expr = te_compile(n, 0, 0, error);
+    if (e->expr == NULL) {
+        return false;
+    }
+
+    return true;
+}
+
+bool dice_expression_roll(dice_expression_t e, int64_t *result)
 {
     double val;
     if (e == NULL || e->expr == NULL) {

tests/test_expr_parse.c

@@ -27,28 +27,28 @@
 
 static void test_expr_parse_none(void **arg)
 {
-    dice_expression_t e = NULL;
+    dice_expression_t e = dice_expression_new();
     int error = 0;
 
-    e = dice_expression_parse("", &error);
-
-    assert_null(e);
+    assert_non_null(e);
+    assert_false(dice_expression_parse(e, "", &error));
     assert_int_equal(error, 1);
+
+    dice_expression_free(e);
 }
 
 static void test_expr_parse_simple(void **arg)
 {
-    dice_expression_t e = NULL;
+    dice_expression_t e = dice_expression_new();
     int error = 0, i = 0;
     int64_t result = 0;
 
-    e = dice_expression_parse("4d6", &error);
-
     assert_non_null(e);
+    assert_true(dice_expression_parse(e, "4d6", &error));
     assert_int_equal(error, 0);
 
     for (i = 0; i < 100000; i++) {
-        assert_true(dice_expression_evaluate(e, &result));
+        assert_true(dice_expression_roll(e, &result));
         assert_true(result >= 4 && result <= 32);
     }
 
@@ -57,17 +57,16 @@ static void test_expr_parse_simple(void **arg)
 
 static void test_expr_parse_modifier(void **arg)
 {
-    dice_expression_t e = NULL;
+    dice_expression_t e = dice_expression_new();
     int error = 0, i = 0;
     int64_t result = 0;
 
-    e = dice_expression_parse("1d20+3+5", &error);
-
     assert_non_null(e);
+    assert_true(dice_expression_parse(e, "1d20+3+5", &error));
     assert_int_equal(error, 0);
 
     for (i = 0; i < 100000; i++) {
-        assert_true(dice_expression_evaluate(e, &result));
+        assert_true(dice_expression_roll(e, &result));
         assert_true(result >= 9 && result <= 28);
     }
 
@@ -76,17 +75,16 @@ static void test_expr_parse_modifier(void **arg)
 
 static void test_expr_parse_complex(void **arg)
 {
-    dice_expression_t e = NULL;
+    dice_expression_t e = dice_expression_new();
     int error = 0, i = 0;
     int64_t result = 0;
 
-    e = dice_expression_parse("1d8+(3+5)+1d6+5d4", &error);
-
     assert_non_null(e);
+    assert_true(dice_expression_parse(e, "1d8+(3+5)+1d6+5d4", &error));
     assert_int_equal(error, 0);
 
     for (i = 0; i < 100000; i++) {
-        assert_true(dice_expression_evaluate(e, &result));
+        assert_true(dice_expression_roll(e, &result));
         assert_true(result >= 15 && result <= 42);
     }