From d4c5edce8fc42f4ea7960e8be1bd3a7875edc883 Mon Sep 17 00:00:00 2001
From: Ian Piumarta <piumarta@gmail.com>
Date: Sat, 25 Jan 2025 13:04:25 +0900
Subject: [PATCH] handle if() and ==

---
 main.leg | 26 +++++++++++++++++++++++---
 test.txt |  5 ++++-
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/main.leg b/main.leg
index 3d680d0..6fccd94 100644
--- a/main.leg
+++ b/main.leg
@@ -1,6 +1,6 @@
 # main.leg -- C parser + interpreter
 #
-# Last edited: 2025-01-25 08:53:25 by piumarta on m1mbp
+# Last edited: 2025-01-25 09:19:51 by piumarta on m1mbp
 
 %{
 ;
@@ -990,6 +990,17 @@ oop toStringOn(oop obj, oop str)
 	    String_append(str, ')');
 	    break;
 	}
+	case If: {
+	    String_format(str, "if (");
+	    toStringOn(get(obj, If,condition), str);
+	    String_format(str, ") ");
+	    toStringOn(get(obj, If,consequent), str);
+	    if (nil != get(obj, If,alternate)) {
+		String_format(str, "; else ");
+		toStringOn(get(obj, If,alternate), str);
+	    }
+	    break;
+	}
 	case While: {
 	    String_format(str, "while (");
 	    toStringOn(get(obj, While,condition), str);
@@ -2113,7 +2124,9 @@ oop eval(oop exp, oop env)
 	    oop cond   = get(exp, If,condition);
 	    oop conseq = get(exp, If,consequent);
 	    oop altern = get(exp, If,alternate);
-	    return isTrue(eval(cond, env)) ? eval(conseq, env) : eval(altern, env);
+	    if (isTrue(eval(cond, env))) eval(conseq, env);
+	    else if (!isNil(altern)) eval(altern, env);
+	    return nil;
 	}
 	case Return: {
 	    nlrReturn(NLR_RETURN, eval(get(exp, Return,value), env));
@@ -2875,7 +2888,7 @@ oop typeCheck(oop exp, oop fntype)
 		case LE: 	assert(!"unimplemented"); 	break;
 		case GE: 	assert(!"unimplemented"); 	break;
 		case GT: 	return t_int;
-		case EQ: 	assert(!"unimplemented"); 	break;
+		case EQ: 	return t_int;
 		case NE: 	assert(!"unimplemented"); 	break;
 		case BAND: 	assert(!"unimplemented"); 	break;
 		case BXOR: 	assert(!"unimplemented"); 	break;
@@ -2892,6 +2905,13 @@ oop typeCheck(oop exp, oop fntype)
 		fatal("incompatible types assigning '%s' to '%s'", toString(rhs), toString(lhs));
 	    return lhs;
 	}
+	case If: {
+	    if (t_int != typeCheck(get(exp, If,condition), fntype)) fatal("if condition is not 'int'");
+	    typeCheck(get(exp, If,consequent), fntype);
+	    if (nil != get(exp, If,alternate))
+		typeCheck(get(exp, If,alternate), fntype);
+	    return nil;
+	}
 	case While: {
 	    oop cond = get(exp, While,condition);
 	    oop body = get(exp, While,expression);
diff --git a/test.txt b/test.txt
index 533ec93..0b48b6b 100755
--- a/test.txt
+++ b/test.txt
@@ -21,7 +21,10 @@ int main(int argc, char **argv)
     printf("x is %d %d\n", x, *p);
     x = 123;
     printf("x is %d %d\n", x, *p);
-    for (x = 0; x < 10; ++x) printf("%d ", x);
+    for (x = 0; x < 10; ++x) {
+	if (x == 5) printf("%%");
+	printf("%d ", x);
+    }
     printf("\n");
     while (x > 0) printf("%d ", --x);
     printf("\n");