WIP: if-then-else, incomplete

source/toy_ast.c

@@ -105,6 +105,17 @@ void Toy_private_emitAstAssert(Toy_Bucket** bucketHandle, Toy_Ast** astHandle, T
 	(*astHandle) = tmp;
 }
 
+void Toy_private_emitAstIfThenElse(Toy_Bucket** bucketHandle, Toy_Ast** astHandle, Toy_Ast* condBranch, Toy_Ast* thenBranch, Toy_Ast* elseBranch) {
+	Toy_Ast* tmp = (Toy_Ast*)Toy_partitionBucket(bucketHandle, sizeof(Toy_Ast));
+
+	tmp->type = TOY_AST_IF_THEN_ELSE;
+	tmp->ifThenElse.condBranch = condBranch;
+	tmp->ifThenElse.thenBranch = thenBranch;
+	tmp->ifThenElse.elseBranch = elseBranch;
+
+	(*astHandle) = tmp;
+}
+
 void Toy_private_emitAstPrint(Toy_Bucket** bucketHandle, Toy_Ast** astHandle) {
 	Toy_Ast* tmp = (Toy_Ast*)Toy_partitionBucket(bucketHandle, sizeof(Toy_Ast));
 

source/toy_ast.h

@@ -18,6 +18,7 @@ typedef enum Toy_AstType {
 	TOY_AST_COMPOUND,
 
 	TOY_AST_ASSERT,
+	TOY_AST_IF_THEN_ELSE,
 	TOY_AST_PRINT,
 
 	TOY_AST_VAR_DECLARE,
@@ -123,6 +124,13 @@ typedef struct Toy_AstAssert {
 	Toy_Ast* message;
 } Toy_AstAssert;
 
+typedef struct Toy_AstIfThenElse {
+	Toy_AstType type;
+	Toy_Ast* condBranch;
+	Toy_Ast* thenBranch;
+	Toy_Ast* elseBranch;
+} Toy_AstIfThenElse;
+
 typedef struct Toy_AstPrint {
 	Toy_AstType type;
 	Toy_Ast* child;
@@ -168,6 +176,7 @@ union Toy_Ast {                     //32 | 64 BITNESS
 	Toy_AstGroup group;             //8  | 16
 	Toy_AstCompound compound;       //16 | 24
 	Toy_AstAssert assert;           //16 | 24
+	Toy_AstIfThenElse ifThenElse;   //16 | 32
 	Toy_AstPrint print;             //8  | 16
 	Toy_AstVarDeclare varDeclare;   //16 | 24
 	Toy_AstVarAssign varAssign;     //16 | 24
@@ -188,6 +197,7 @@ void Toy_private_emitAstGroup(Toy_Bucket** bucketHandle, Toy_Ast** astHandle);
 void Toy_private_emitAstCompound(Toy_Bucket** bucketHandle, Toy_Ast** astHandle,Toy_AstFlag flag, Toy_Ast* right);
 
 void Toy_private_emitAstAssert(Toy_Bucket** bucketHandle, Toy_Ast** astHandle, Toy_Ast* child, Toy_Ast* msg);
+void Toy_private_emitAstIfThenElse(Toy_Bucket** bucketHandle, Toy_Ast** astHandle, Toy_Ast* condBranch, Toy_Ast* thenBranch, Toy_Ast* elseBranch);
 void Toy_private_emitAstPrint(Toy_Bucket** bucketHandle, Toy_Ast** astHandle);
 
 void Toy_private_emitAstVariableDeclaration(Toy_Bucket** bucketHandle, Toy_Ast** astHandle, Toy_String* name, Toy_Ast* expr);

source/toy_opcodes.h

@@ -32,6 +32,7 @@ typedef enum Toy_OpcodeType {
 
 	//control instructions
 	TOY_OPCODE_RETURN,
+	TOY_OPCODE_JUMP,
 
 	TOY_OPCODE_SCOPE_PUSH,
 	TOY_OPCODE_SCOPE_POP,
@@ -48,3 +49,16 @@ typedef enum Toy_OpcodeType {
 	TOY_OPCODE_ERROR,
 	TOY_OPCODE_EOF = 255,
 } Toy_OpcodeType;
+
+//specific opcode flags
+typedef enum Toy_OpParamJumpType {
+	TOY_OP_PARAM_JUMP_ABSOLUTE = 0, //from the start of the routine's code section
+	TOY_OP_PARAM_JUMP_RELATIVE = 1,
+} Toy_OpJumpType;
+
+typedef enum Toy_OpParamJumpConditional {
+	TOY_OP_PARAM_JUMP_ALWAYS = 0,
+	TOY_OP_PARAM_JUMP_IF_TRUE = 1,
+	TOY_OP_PARAM_JUMP_IF_FALSE = 2,
+} Toy_OpParamJumpConditional;
+

source/toy_parser.c

@@ -655,6 +655,7 @@ static void makeExpr(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** ro
 
 //forward declarations
 static void makeBlockStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** rootHandle);
+static void makeDeclarationStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** rootHandle);
 
 static void makeAssertStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** rootHandle) {
 	Toy_Ast* ast = NULL; //assert's emit function is a bit different
@@ -677,6 +678,27 @@ static void makeAssertStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_As
 	consume(parser, TOY_TOKEN_OPERATOR_SEMICOLON, "Expected ';' at the end of assert statement");
 }
 
+static void makeIfThenElseStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** rootHandle) {
+	Toy_Ast* condBranch = NULL;
+	Toy_Ast* thenBranch = NULL;
+	Toy_Ast* elseBranch = NULL;
+
+	//if (condBranch)
+	consume(parser, TOY_TOKEN_OPERATOR_PAREN_LEFT, "Expected '(' after 'if' keyword");
+	makeExpr(bucketHandle, parser, &condBranch);
+	consume(parser, TOY_TOKEN_OPERATOR_PAREN_RIGHT, "Expected ')' after 'if' condition");
+
+	// { thenBranch }
+	makeDeclarationStmt(bucketHandle, parser, &thenBranch);
+
+	//else { elseBranch }
+	if (match(parser, TOY_TOKEN_KEYWORD_ELSE)) {
+		makeDeclarationStmt(bucketHandle, parser, &elseBranch);
+	}
+
+	Toy_private_emitAstIfThenElse(bucketHandle, rootHandle, condBranch, thenBranch, elseBranch);
+}
+
 static void makePrintStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** rootHandle) {
 	makeExpr(bucketHandle, parser, rootHandle);
 	Toy_private_emitAstPrint(bucketHandle, rootHandle);
@@ -737,12 +759,18 @@ static void makeStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** ro
 		return;
 	}
 
+	//assert
 	else if (match(parser, TOY_TOKEN_KEYWORD_ASSERT)) {
 		makeAssertStmt(bucketHandle, parser, rootHandle);
 		return;
 	}
 
 	//if-then-else
+	else if (match(parser, TOY_TOKEN_KEYWORD_IF)) {
+		makeIfThenElseStmt(bucketHandle, parser, rootHandle);
+		return;
+	}
+
 	//while-then
 	//for-pre-clause-post-then
 	//break
@@ -750,17 +778,19 @@ static void makeStmt(Toy_Bucket** bucketHandle, Toy_Parser* parser, Toy_Ast** ro
 	//return
 	//import
 
-	//check for empty lines
-	else if (match(parser, TOY_TOKEN_OPERATOR_SEMICOLON)) {
-		Toy_private_emitAstPass(bucketHandle, rootHandle);
-		return;
-	}
-
+	//print
 	else if (match(parser, TOY_TOKEN_KEYWORD_PRINT)) {
 		makePrintStmt(bucketHandle, parser, rootHandle);
 		return;
 	}
 
+	//empty lines
+	else if (match(parser, TOY_TOKEN_OPERATOR_SEMICOLON)) {
+		Toy_private_emitAstPass(bucketHandle, rootHandle);
+		return;
+	}
+
+	//expressions
 	else {
 		//default
 		makeExprStmt(bucketHandle, parser, rootHandle);

source/toy_routine.c

@@ -47,11 +47,22 @@ static void emitFloat(void** handle, unsigned int* capacity, unsigned int* count
 
 //write instructions based on the AST types
 #define EMIT_BYTE(rt, part, byte) \
-	emitByte((void**)(&((*rt)->part)), &((*rt)->part##Capacity), &((*rt)->part##Count), byte);
+	emitByte((void**)(&((*rt)->part)), &((*rt)->part##Capacity), &((*rt)->part##Count), byte)
 #define EMIT_INT(rt, part, bytes) \
-	emitInt((void**)(&((*rt)->part)), &((*rt)->part##Capacity), &((*rt)->part##Count), bytes);
+	emitInt((void**)(&((*rt)->part)), &((*rt)->part##Capacity), &((*rt)->part##Count), bytes)
 #define EMIT_FLOAT(rt, part, bytes) \
-	emitFloat((void**)(&((*rt)->part)), &((*rt)->part##Capacity), &((*rt)->part##Count), bytes);
+	emitFloat((void**)(&((*rt)->part)), &((*rt)->part##Capacity), &((*rt)->part##Count), bytes)
+
+//skip bytes, but return the address
+#define SKIP_BYTE(rt, part) (EMIT_BYTE(rt, part, 0), ((*rt)->part##Count - 1))
+#define SKIP_INT(rt, part) (EMIT_INT(rt, part, 0), ((*rt)->part##Count - 4))
+
+//overwrite a pre-existing position
+#define OVERWRITE_INT(rt, part, addr, bytes) \
+	emitInt((void**)(&((*rt)->part)), &((*rt)->part##Capacity), &(addr), bytes);
+
+//simply get the address (always an integer)
+#define CURRENT_ADDRESS(rt, part) ((*rt)->part##Count)
 
 static void emitToJumpTable(Toy_Routine** rt, unsigned int startAddr) {
 	EMIT_INT(rt, code, (*rt)->jumpsCount); //mark the jump index in the code
@@ -296,6 +307,48 @@ static unsigned int writeInstructionAssert(Toy_Routine** rt, Toy_AstAssert ast)
 	return 0;
 }
 
+static unsigned int writeInstructionIfThenElse(Toy_Routine** rt, Toy_AstIfThenElse ast) {
+	//cond-branch
+	writeRoutineCode(rt, ast.condBranch);
+
+	//emit the jump word (opcode, type, condition, padding)
+	EMIT_BYTE(rt, code, TOY_OPCODE_JUMP);
+	EMIT_BYTE(rt, code, TOY_OP_PARAM_JUMP_RELATIVE);
+	EMIT_BYTE(rt, code, TOY_OP_PARAM_JUMP_IF_FALSE);
+	EMIT_BYTE(rt, code, 0);
+
+	unsigned int thenEndAddr = SKIP_INT(rt, code); //parameter to be written later
+
+	//emit then branch
+	writeRoutineCode(rt, ast.thenBranch);
+
+	if (ast.elseBranch != NULL) {
+		//emit the jump-to-end (opcode, type, condition, padding)
+		EMIT_BYTE(rt, code, TOY_OPCODE_JUMP);
+		EMIT_BYTE(rt, code, TOY_OP_PARAM_JUMP_RELATIVE);
+		EMIT_BYTE(rt, code, TOY_OP_PARAM_JUMP_ALWAYS);
+		EMIT_BYTE(rt, code, 0);
+
+		unsigned int elseEndAddr = SKIP_INT(rt, code); //parameter to be written later
+
+		//specify the starting position for the else branch
+		OVERWRITE_INT(rt, code, thenEndAddr, CURRENT_ADDRESS(rt, code) - thenEndAddr);
+
+		//emit the else branch
+		writeRoutineCode(rt, ast.elseBranch);
+
+		//specify the ending position for the else branch
+		OVERWRITE_INT(rt, code, elseEndAddr, CURRENT_ADDRESS(rt, code) - elseEndAddr);
+	}
+
+	else {
+		//without an else branch, set the jump destination and move on
+		OVERWRITE_INT(rt, code, thenEndAddr, CURRENT_ADDRESS(rt, code) - thenEndAddr);
+	}
+
+	return 0;
+}
+
 static unsigned int writeInstructionPrint(Toy_Routine** rt, Toy_AstPrint ast) {
 	//the thing to print
 	writeRoutineCode(rt, ast.child);
@@ -494,6 +547,7 @@ static unsigned int writeRoutineCode(Toy_Routine** rt, Toy_Ast* ast) {
 		return 0;
 	}
 
+	//NOTE: 'result' is used to in 'writeInstructionCompound()'
 	unsigned int result = 0;
 
 	//determine how to write each instruction based on the Ast
@@ -545,6 +599,10 @@ static unsigned int writeRoutineCode(Toy_Routine** rt, Toy_Ast* ast) {
 			result += writeInstructionAssert(rt, ast->assert);
 			break;
 
+		case TOY_AST_IF_THEN_ELSE:
+			result += writeInstructionIfThenElse(rt, ast->ifThenElse);
+			break;
+
 		case TOY_AST_PRINT:
 			result += writeInstructionPrint(rt, ast->print);
 			break;
@@ -596,7 +654,7 @@ static void* writeRoutine(Toy_Routine* rt, Toy_Ast* ast) {
 	//write the header and combine the parts
 	void* buffer = NULL;
 	unsigned int capacity = 0, count = 0;
-	// int paramAddr = 0, codeAddr = 0, subsAddr = 0;
+	// int paramAddr = 0, subsAddr = 0;
 	int codeAddr = 0;
 	int jumpsAddr = 0;
 	int dataAddr = 0;

source/toy_vm.c

@@ -31,7 +31,7 @@ static inline int readPostfixUtil(unsigned int* ptr, int amount) {
 
 static inline void fixAlignment(Toy_VM* vm) {
 	//NOTE: It's a tilde, not a negative sign
-	vm->programCounter = (vm->programCounter + 3) & ~0b11;
+	vm->programCounter = (vm->programCounter + 3) & ~3;
 }
 
 //instruction handlers
@@ -361,6 +361,52 @@ static void processLogical(Toy_VM* vm, Toy_OpcodeType opcode) {
 	}
 }
 
+static void processJump(Toy_VM* vm) {
+	Toy_OpJumpType type = READ_BYTE(vm);
+	Toy_OpParamJumpConditional cond = READ_BYTE(vm);
+	fixAlignment(vm);
+
+	//assume the param is a signed integer
+	int param = READ_INT(vm);
+
+	//should we jump?
+	switch(cond) {
+		case TOY_OP_PARAM_JUMP_ALWAYS:
+			break;
+
+		case TOY_OP_PARAM_JUMP_IF_TRUE: {
+			Toy_Value value = Toy_popStack(&vm->stack);
+			if (Toy_checkValueIsTruthy(value) == true) {
+				Toy_freeValue(value);
+				break;
+			}
+			Toy_freeValue(value);
+			return;
+		}
+
+		case TOY_OP_PARAM_JUMP_IF_FALSE: {
+			Toy_Value value = Toy_popStack(&vm->stack);
+			if (Toy_checkValueIsTruthy(value) != true) {
+				Toy_freeValue(value);
+				break;
+			}
+			Toy_freeValue(value);
+			return;
+		}
+	}
+
+	//do the jump
+	switch(type) {
+		case TOY_OP_PARAM_JUMP_ABSOLUTE:
+			vm->programCounter = vm->codeAddr + param;
+			return;
+
+		case TOY_OP_PARAM_JUMP_RELATIVE:
+			vm->programCounter += param;
+			return;
+	}
+}
+
 static void processAssert(Toy_VM* vm) {
 	unsigned int count = READ_BYTE(vm);
 
@@ -551,6 +597,10 @@ static void process(Toy_VM* vm) {
 				//temp terminator
 				return;
 
+			case TOY_OPCODE_JUMP:
+				processJump(vm);
+				break;
+
 			case TOY_OPCODE_SCOPE_PUSH:
 				vm->scope = Toy_pushScope(&vm->scopeBucket, vm->scope);
 				break;