changed operator priority

2022-04-02 22:35:21 +02:00
parent 6c0e03f824
commit d03bb4937d
4 changed files with 191 additions and 40 deletions
@@ -0,0 +1,78 @@
+
+fun is_space(c)
+    return c == ' ' 
+        or c == '\t' 
+        or c == '\n';
+
+fun is_digit(c)
+    return unicode(c) <= unicode('9')
+       and unicode(c) >= unicode('0');
+
+fun skip(ctx, test)
+    while not ended(ctx) and test(current(ctx)):
+        next(ctx);
+
+fun ended(ctx)
+    return ctx.i == count(ctx.str);
+
+fun next(ctx) {
+    assert(ctx.i < count(ctx.str));
+    ctx.i = ctx.i + 1;
+}
+
+fun current(ctx)
+    return ctx.str[ctx.i];
+
+fun parse(str) {
+
+    if str == none: 
+        str = '';
+
+    ctx = {str: str, i: 0};
+
+    skip(ctx, is_space);
+
+    if ended(ctx):
+        # JSON source string only contains whitespace.
+        return none;
+
+    return parse_any_value(ctx);
+}
+
+fun parse_any_value(ctx) {
+
+    if is_digit(current(ctx)): {
+        # Number (int or float)
+        parsed = 0;
+        while not ended(ctx) and is_digit(current(ctx)): {
+            parsed = parsed * 10 + unicode(current(ctx)) - unicode('0');
+            next(ctx);
+        }
+
+        if current(ctx) == '.': {
+
+            next(ctx);
+
+            if ended(ctx):
+                # Source string ended unexpectedly after dot.
+                return none;
+
+            if not is_digit(current(ctx)):
+                # Got something other than a digit after dot.
+                return none;
+
+            fact = 1;
+            while not ended(ctx) and is_digit(current(ctx)): {
+                fact = fact / 10.0;
+                parsed = parsed + fact * (unicode(current(ctx)) - unicode('0'));
+                next(ctx);
+            }
+        }
+        
+        return parsed;
+    }
+
+    assert(false);
+}
+
+parse();
@@ -131,6 +131,7 @@ static Node *parse_ifelse_statement(Context *ctx);
 static Node *parse_compound_statement(Context *ctx, TokenKind end);
 static Node *parse_function_definition(Context *ctx);
 static Node *parse_postfix_expression(Context *ctx);
+static Node *parse_prefix_expression(Context *ctx);
 static Node *parse_while_statement(Context *ctx);
 static Node *parse_dowhile_statement(Context *ctx);

@@ -865,7 +866,6 @@ static Node *parse_list_primary_expression(Context *ctx)
 						
 }

-
 static Node *parse_map_primary_expression(Context *ctx)
 {
 	assert(ctx != NULL);
@@ -1067,42 +1067,6 @@ static Node *parse_primary_expresion(Context *ctx)

 	switch(current(ctx))
 		{
-			case '+':
-			case '-':
-			case TKWNOT:
-			{
-				Token *unary_operator = current_token(ctx);
-
-				next(ctx);
-
-				Node *operand = parse_primary_expresion(ctx);
-				
-				if(operand == NULL) 
-					return NULL;
-
-				OperExprNode *temp = BPAlloc_Malloc(ctx->alloc, sizeof(OperExprNode));
-				{
-					if(temp == NULL)
-						return NULL;
-
-					temp->base.base.kind = NODE_EXPR;
-					temp->base.base.next = NULL;
-					temp->base.base.offset = unary_operator->offset;
-					temp->base.base.length = operand->offset + operand->length - unary_operator->offset;
-					temp->head = operand;
-					temp->count = 1;
-
-					switch(unary_operator->kind)
-						{
-							case '+': temp->base.kind = EXPR_POS; break;
-							case '-': temp->base.kind = EXPR_NEG; break;
-							case TKWNOT: temp->base.kind = EXPR_NOT; break;
-							default: assert(0); break;
-						}
-				}
-				return (Node*) temp;
-			}
-
 			case '[':
 			return parse_list_primary_expression(ctx);

@@ -1504,6 +1468,64 @@ done:
 	return node;
 }

+static Node *parse_prefix_expression(Context *ctx)
+{
+	if(done(ctx))
+		{
+			Error_Report(ctx->error, 0, "Source ended where a prefix expression was expected");
+			return NULL;
+		}
+
+	switch(current(ctx))
+		{
+			case TDONE:
+			Error_Report(ctx->error, 1, "Unexpected end of source where a prefix expression was expected");
+			return NULL;
+
+			case '+':
+			case '-':
+			case TKWNOT:
+			{
+				Token *unary_operator = current_token(ctx);
+
+				next(ctx);
+
+				Node *operand = parse_prefix_expression(ctx);
+				
+				if(operand == NULL) 
+					return NULL;
+
+				OperExprNode *temp = BPAlloc_Malloc(ctx->alloc, sizeof(OperExprNode));
+				{
+					if(temp == NULL)
+						return NULL;
+
+					temp->base.base.kind = NODE_EXPR;
+					temp->base.base.next = NULL;
+					temp->base.base.offset = unary_operator->offset;
+					temp->base.base.length = operand->offset + operand->length - unary_operator->offset;
+					temp->head = operand;
+					temp->count = 1;
+
+					switch(unary_operator->kind)
+						{
+							case '+': temp->base.kind = EXPR_POS; break;
+							case '-': temp->base.kind = EXPR_NEG; break;
+							case TKWNOT: temp->base.kind = EXPR_NOT; break;
+							default: assert(0); break;
+						}
+				}
+				return (Node*) temp;
+			}
+
+			default:
+			return parse_postfix_expression(ctx);
+		}
+
+	UNREACHABLE;
+	return NULL;
+}
+
 static inline _Bool isbinop(Token *tok)
 {
 	assert(tok != NULL);
@@ -1577,7 +1599,7 @@ static Node *parse_expression_2(Context *ctx, Node *left_expr, int min_prec)

 			next(ctx);

-			Node *right_expr = parse_postfix_expression(ctx);
+			Node *right_expr = parse_prefix_expression(ctx);

 			if(right_expr == NULL)
 				return NULL;
@@ -1640,7 +1662,7 @@ static Node *parse_expression_2(Context *ctx, Node *left_expr, int min_prec)

 static Node *parse_expression(Context *ctx)
 {
-	Node *left_expr = parse_postfix_expression(ctx);
+	Node *left_expr = parse_prefix_expression(ctx);

 	if(left_expr == NULL)
 		return NULL;
@@ -49,6 +49,7 @@ static void print(Object *obj, FILE *fp);
 static char *to_string(Object *self, int *size, Heap *heap, Error *err);
 static _Bool op_eql(Object *self, Object *other);
 static void walkexts(Object *self, void (*callback)(void **referer, unsigned int size, void *userp), void *userp);
+static Object *select(Object *self, Object *key, Heap *heap, Error *error);

 static TypeObject t_string = {
 	.base = (Object) { .type = &t_type, .flags = Object_STATIC },
@@ -59,11 +60,61 @@ static TypeObject t_string = {
 	.count = count,
 	.copy = copy,
 	.print = print,
+	.select = select,
 	.to_string = to_string,
 	.op_eql = op_eql,
 	.walkexts = walkexts,
 };

+static int char_index_to_offset(StringObject *str, int idx)
+{
+	// Iterate over a string to find the first byte of
+	// the utf-8 character number [idx].
+
+	int scanned_bytes = 0, 
+	    last_code_len = 0;
+
+	while(idx > 0)
+		{
+			last_code_len = utf8_sequence_to_utf32_codepoint(str->body + scanned_bytes, str->bytes - scanned_bytes, NULL);
+			scanned_bytes += last_code_len;
+			idx -= 1;
+
+			assert(scanned_bytes <= str->bytes);
+		}
+
+	assert(idx == 0);
+	return scanned_bytes;
+}
+
+static Object *select(Object *self, Object *key, Heap *heap, Error *error)
+{
+	assert(self != NULL && self->type == &t_string);
+	assert(key != NULL && heap != NULL && error != NULL);
+
+	if(!Object_IsInt(key))
+		{
+			Error_Report(error, 0, "Non integer key");
+			return NULL;
+		}
+
+	int idx = Object_ToInt(key, error);
+	assert(error->occurred == 0);
+
+	StringObject *str = (StringObject*) self;
+
+	if(idx < 0 || idx >= str->count)
+		{
+			Error_Report(error, 0, "Out of range index");
+			return NULL;
+		}
+
+	int byteoffset = char_index_to_offset(str, idx);
+	int codelength = utf8_sequence_to_utf32_codepoint(str->body + byteoffset, str->bytes - byteoffset, NULL);
+
+	return Object_FromString(str->body + byteoffset, codelength, heap, error);
+}
+
 static char *to_string(Object *self, int *size, Heap *heap, Error *err)
 {
 	assert(self != NULL);