syntax: allow empty switch statements

Also add testcases for switch/case blocks.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

2 files changed, 181 insertions, 0 deletions

diff --git a/parser.y b/parser.y
index 1d71a16..938a341 100644
--- a/parser.y
+++ b/parser.y
@@ -177,6 +177,8 @@ try_catch_block(A) ::= empty_object.					{ A = 0; }
 
 switch_stmt(A) ::= T_SWITCH(B) T_LPAREN exp(C) T_RPAREN T_LBRACE switch_cases(D) T_RBRACE.
 														{ A = wrap_op(B, C, D); }
+switch_stmt(A) ::= T_SWITCH T_LPAREN exp(B) T_RPAREN empty_object.
+														{ A = B; }
 
 switch_cases(A) ::= switch_cases(B) switch_case(C).		{ A = append_op(B, C); }
 switch_cases(A) ::= switch_case(B).						{ A = B; }
diff --git a/tests/02_runtime/04_switch_case b/tests/02_runtime/04_switch_case
new file mode 100644
index 0000000..9a871fd
--- /dev/null
+++ b/tests/02_runtime/04_switch_case
@@ -0,0 +1,179 @@
+Testing utpl switch statements.
+
+
+1. Ensure that execution starts at the first matching case.
+
+-- Expect stdout --
+1a
+-- End --
+
+-- Testcase --
+{%
+	switch (1) {
+	case 1:
+		print("1a\n");
+		break;
+
+	case 1:
+		print("1b\n");
+		break;
+
+	case 2:
+		print("2\n");
+		break;
+	}
+%}
+-- End --
+
+
+2. Ensure that default case is only used if no case matches,
+   even if declared first.
+
+-- Expect stdout --
+1
+default
+-- End --
+
+-- Testcase --
+{%
+	for (n in [1, 3]) {
+		switch (n) {
+		default:
+			print("default\n");
+			break;
+
+		case 1:
+			print("1\n");
+			break;
+
+		case 2:
+			print("2\n");
+			break;
+		}
+	}
+%}
+-- End --
+
+
+3. Ensure that cases without break fall through into
+   subsequent cases.
+
+-- Expect stdout --
+1
+2
+default
+1
+2
+-- End --
+
+-- Testcase --
+{%
+	for (n in [1, 3]) {
+		switch (n) {
+		default:
+			print("default\n");
+
+		case 1:
+			print("1\n");
+
+		case 2:
+			print("2\n");
+		}
+	}
+%}
+-- End --
+
+
+4. Ensure that duplicate default cases emit a syntax
+   error during parsing.
+
+-- Expect stderr --
+Syntax error: more than one switch default case
+In line 6, byte 9:
+
+ `        default:`
+  Near here -----^
+
+
+-- End --
+
+-- Testcase --
+{%
+	switch (1) {
+		default:
+			print("default1\n");
+
+		default:
+			print("default2\n");
+	}
+%}
+-- End --
+
+
+5. Ensure that case values use strict comparison.
+
+-- Expect stdout --
+b
+b
+-- End --
+
+-- Testcase --
+{%
+	switch (1.0) {
+	case 1:
+		print("a\n");
+		break;
+
+	case 1.0:
+		print("b\n");
+		break;
+	}
+
+	switch ("123") {
+	case 123:
+		print("a\n");
+		break;
+
+	case "123":
+		print("b\n");
+		break;
+	}
+%}
+-- End --
+
+
+6. Ensure that case values may be complex expressions.
+
+-- Expect stdout --
+2, 3, 1
+-- End --
+
+-- Testcase --
+{%
+	switch (1) {
+	case a = 2, b = 3, c = 1:
+		print(join(", ", [ a, b, c ]), "\n");
+		break;
+	}
+%}
+-- End --
+
+
+7. Ensure that empty switch statements are accepted by the
+   parser and that the test expression is evaluated.
+
+-- Expect stdout --
+true
+-- End --
+
+-- Testcase --
+{%
+	x = false;
+
+	switch (x = true) {
+
+	}
+
+	print(x, "\n");
+%}
+-- End --