From a65f2dcf81caea8b694180566d51798f8a212635 Mon Sep 17 00:00:00 2001
From: "K. Lange" <klange@toaruos.org>
Date: Mon, 1 Mar 2021 11:55:51 +0900
Subject: [PATCH] Add 'assert' statement

---
 src/compiler.c             | 23 +++++++++++++++++++++++
 src/exceptions.c           |  1 +
 src/rline.c                |  2 +-
 src/scanner.c              |  6 +++++-
 src/scanner.h              |  1 +
 src/vm.h                   |  1 +
 test/testAssert.krk        | 14 ++++++++++++++
 test/testAssert.krk.expect |  2 ++
 8 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 test/testAssert.krk
 create mode 100644 test/testAssert.krk.expect

diff --git a/src/compiler.c b/src/compiler.c
index f02d2d6..83f12d3 100644
--- a/src/compiler.c
+++ b/src/compiler.c
@@ -1734,6 +1734,27 @@ static void delStatement() {
 	inDel = 0;
 }
 
+static void assertStatement() {
+	expression();
+	int elseJump = emitJump(OP_JUMP_IF_TRUE);
+
+	KrkToken assertionError = syntheticToken("AssertionError");
+	size_t ind = identifierConstant(&assertionError);
+	EMIT_CONSTANT_OP(OP_GET_GLOBAL, ind);
+	int args = 0;
+
+	if (match(TOKEN_COMMA)) {
+		expression();
+		args = 1;
+	}
+
+	EMIT_CONSTANT_OP(OP_CALL, args);
+	emitByte(OP_RAISE);
+
+	patchJump(elseJump);
+	emitByte(OP_POP);
+}
+
 static void statement() {
 	if (match(TOKEN_EOL) || match(TOKEN_EOF)) {
 		return; /* Meaningless blank line */
@@ -1766,6 +1787,8 @@ _anotherSimpleStatement:
 			continueStatement();
 		} else if (match(TOKEN_DEL)) {
 			delStatement();
+		} else if (match(TOKEN_ASSERT)) {
+			assertStatement();
 		} else if (match(TOKEN_PASS)) {
 			/* Do nothing. */
 		} else {
diff --git a/src/exceptions.c b/src/exceptions.c
index d19ed67..3e5a4dc 100644
--- a/src/exceptions.c
+++ b/src/exceptions.c
@@ -158,6 +158,7 @@ void _createAndBind_exceptions(void) {
 	ADD_EXCEPTION_CLASS(vm.exceptions->keyboardInterrupt, "KeyboardInterrupt", vm.exceptions->baseException);
 	ADD_EXCEPTION_CLASS(vm.exceptions->zeroDivisionError, "ZeroDivisionError", vm.exceptions->baseException);
 	ADD_EXCEPTION_CLASS(vm.exceptions->notImplementedError, "NotImplementedError", vm.exceptions->baseException);
+	ADD_EXCEPTION_CLASS(vm.exceptions->assertionError, "AssertionError", vm.exceptions->baseException);
 	ADD_EXCEPTION_CLASS(vm.exceptions->syntaxError, "SyntaxError", vm.exceptions->baseException);
 	krk_defineNative(&vm.exceptions->syntaxError->methods, ".__str__", _syntaxerror_str);
 	krk_finalizeClass(vm.exceptions->syntaxError);
diff --git a/src/rline.c b/src/rline.c
index 3d35bb2..9ac53dc 100644
--- a/src/rline.c
+++ b/src/rline.c
@@ -544,7 +544,7 @@ char * syn_krk_keywords[] = {
 	"and","class","def","else","for","if","in","import","del",
 	"let","not","or","return","while","try","except","raise",
 	"continue","break","as","from","elif","lambda","with","is",
-	"pass",
+	"pass","assert",
 	NULL
 };
 
diff --git a/src/scanner.c b/src/scanner.c
index 6f0cdc1..f1ce95c 100644
--- a/src/scanner.c
+++ b/src/scanner.c
@@ -197,7 +197,11 @@ static KrkTokenType identifierType() {
 	switch (*scanner.start) {
 		case 'a': if (MORE(1)) switch(scanner.start[1]) {
 			case 'n': return checkKeyword(2, "d", TOKEN_AND);
-			case 's': return checkKeyword(2, "", TOKEN_AS);
+			case 's': if (MORE(2)) {
+					return checkKeyword(2, "sert", TOKEN_ASSERT);
+				} else {
+					return checkKeyword(2, "", TOKEN_AS);
+				}
 		} break;
 		case 'b': if (MORE(1)) return checkKeyword(1, "reak", TOKEN_BREAK);
 			else if (scanner.start[1] == '\'' || scanner.start[1] == '"') return TOKEN_PREFIX_B;
diff --git a/src/scanner.h b/src/scanner.h
index aba1b9a..19b17b0 100644
--- a/src/scanner.h
+++ b/src/scanner.h
@@ -90,6 +90,7 @@ typedef enum {
 	TOKEN_AS,
 	TOKEN_FROM,
 	TOKEN_LAMBDA,
+	TOKEN_ASSERT,
 	TOKEN_WITH,
 
 	TOKEN_PREFIX_B,
diff --git a/src/vm.h b/src/vm.h
index dda57fe..678fd7b 100644
--- a/src/vm.h
+++ b/src/vm.h
@@ -120,6 +120,7 @@ struct Exceptions {
 	KrkClass * zeroDivisionError;   /**< @exception ZeroDivisionError A mathematical function attempted to divide by zero. */
 	KrkClass * notImplementedError; /**< @exception NotImplementedError The method is not implemented, either for the given arguments or in general. */
 	KrkClass * syntaxError;         /**< @exception SyntaxError The compiler encountered an unrecognized or invalid source code input. */
+	KrkClass * assertionError;      /**< @exception AssertionError An @c assert statement failed. */
 };
 
 /**
diff --git a/test/testAssert.krk b/test/testAssert.krk
new file mode 100644
index 0000000..870fa83
--- /dev/null
+++ b/test/testAssert.krk
@@ -0,0 +1,14 @@
+
+
+assert 1 + 1
+assert True, "Test"
+
+try:
+    assert False
+except AssertionError:
+    print("Pass")
+
+try:
+    assert False, "with a message"
+except AssertionError as e:
+    print("msg =", str(e))
diff --git a/test/testAssert.krk.expect b/test/testAssert.krk.expect
new file mode 100644
index 0000000..8a262b7
--- /dev/null
+++ b/test/testAssert.krk.expect
@@ -0,0 +1,2 @@
+Pass
+msg = with a message