From 26a1adffd4ac7b4f1390ba0135ede850697c4dfa Mon Sep 17 00:00:00 2001
From: Danny van Kooten <dannyvankooten@users.noreply.github.com>
Date: Fri, 20 Mar 2020 12:11:20 +0100
Subject: add string equality operators

---
 src/template.c        | 27 +++++++++++++++++++++------
 tests/test_template.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/src/template.c b/src/template.c
index 9e739bc..a1439c4 100644
--- a/src/template.c
+++ b/src/template.c
@@ -100,7 +100,7 @@ mpc_parser_t *parser_init() {
         "           | <lexp> <spaces> \"!=\" <spaces> <lexp> "
         "           | <lexp> <spaces> \"==\" <spaces> <lexp> "
         "           | <lexp> ;"
-        " print     : /{{2}-? */ <lexp> / *-?}}/ ;"
+        " print     : /{{2}-? */ <expression> / *-?}}/ ;"
         " comment   : \"{#\" /[^#][^#}]*/ \"#}\" ;"
         " statement_open: /{\%-? */;"
         " statement_close: / *-?\%}/;"
@@ -366,13 +366,28 @@ struct unja_object *eval_expression_value(mpc_ast_t* node, struct context *ctx)
     return &null_object;
 }
 
+struct unja_object *eval_string_infix_expression(struct unja_object *left, char *op, struct unja_object *right) {
+    struct unja_object *result;
+
+    if (strcmp(op, "+") == 0) {
+        result = make_string_object(left->string, right->string);
+    } else if (strcmp(op, "==") == 0) {
+        result = make_int_object(strcmp(left->string, right->string) == 0);
+    } else if(strcmp(op, "!=") == 0) {
+        result = make_int_object(strcmp(left->string, right->string) != 0);
+    } else {
+        errx(EXIT_FAILURE, "invalid string operator: %s", op);
+    }
+
+    object_free(left);
+    object_free(right);
+    return result;
+}
+
 struct unja_object *eval_infix_expression(struct unja_object *left, char *op, struct unja_object *right) {
     /* if operator is + and either left or right node is of type string: concat */
-    if (op[0] == '+' && (left->type == OBJ_STRING && right->type == OBJ_STRING)) {           
-        struct unja_object *result = make_string_object(left->string, right->string);
-        object_free(left);
-        object_free(right);
-        return result;
+    if (left->type == OBJ_STRING && right->type == OBJ_STRING) {           
+        return eval_string_infix_expression(left, op, right);
     } 
 
     int result;
diff --git a/tests/test_template.c b/tests/test_template.c
index 039e993..d94ddd6 100644
--- a/tests/test_template.c
+++ b/tests/test_template.c
@@ -309,6 +309,22 @@ TEST(expr_eq) {
     }
 }
 
+TEST(expr_string_eq) {
+   struct {
+        char *input;
+        char *expected_output;
+    } tests[] = {
+        {"{% if \"foo\" == \"bar\" %}1{% endif %}", ""},
+        {"{% if \"foo\" == \"foo\" %}1{% endif %}", "1"},
+    };
+
+    for (int i=0; i < ARRAY_SIZE(tests); i++) {
+        char *output = template_string(tests[i].input, NULL);
+        assert_str(output, tests[i].expected_output);
+        free(output);
+    }
+}
+
 TEST(expr_not_eq) {
    struct {
         char *input;
@@ -325,6 +341,22 @@ TEST(expr_not_eq) {
     }
 }
 
+TEST(expr_string_not_eq) {
+   struct {
+        char *input;
+        char *expected_output;
+    } tests[] = {
+        {"{% if \"foo\" != \"bar\" %}1{% endif %}", "1"},
+        {"{% if \"foo\" != \"foo\" %}1{% endif %}", ""},
+    };
+
+    for (int i=0; i < ARRAY_SIZE(tests); i++) {
+        char *output = template_string(tests[i].input, NULL);
+        assert_str(output, tests[i].expected_output);
+        free(output);
+    }
+}
+
 TEST(if_block_whitespace) {
     char *input = "\n{%- if 10 > 5 -%}\nOK\n{%- endif -%}\n";
     char *output = template_string(input, NULL);
-- 
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