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block statement lists never get fake expressions

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instead blocks have a field that encodes whether the last statement ended with
a semicolon.
This commit is contained in:
Josh Wolfe 2017-04-12 22:18:56 -07:00
parent 919910312d
commit 356424916c
4 changed files with 64 additions and 81 deletions
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4
src/all_types.hpp
View File

@ -410,10 +410,8 @@ struct AstNodeParamDecl {
};
struct AstNodeBlock {
// the final statement is the returned expression.
// if there are no statements, the returned expression is void.
// the final statement is never a label.
ZigList<AstNode *> statements;
bool last_statement_is_result_expression;
};
enum ReturnKind {

4
src/ast_render.cpp
View File

@ -464,8 +464,10 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
}
print_indent(ar);
render_node_grouped(ar, statement);
if (i != node->data.block.statements.length - 1)
if (!(i == node->data.block.statements.length - 1 &&
node->data.block.last_statement_is_result_expression)) {
fprintf(ar->f, ";");
}
fprintf(ar->f, "\n");
}
ar->indent -= ar->indent_size;

13
src/ir.cpp
View File

@ -3378,6 +3378,7 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
// a label is an entry point
is_continuation_unreachable = false;
return_value = nullptr;
continue;
}
@ -3406,7 +3407,8 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
child_scope = decl_var_instruction->var->child_scope;
} else {
// label, defer, variable declaration will never be the last statement
if (i == block_node->data.block.statements.length - 1) {
if (block_node->data.block.last_statement_is_result_expression &&
i == block_node->data.block.statements.length - 1) {
// this is the result value statement
return_value = statement_value;
} else {
@ -3422,13 +3424,18 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
}
}
assert(return_value != nullptr);
if (!is_continuation_unreachable) {
// control flow falls out of block
if (!block_node->data.block.last_statement_is_result_expression) {
assert(return_value == nullptr);
return_value = ir_mark_gen(ir_build_const_void(irb, child_scope, block_node));
}
ir_gen_defers_for_block(irb, child_scope, outer_block_scope, false, false);
}
assert(return_value != nullptr);
return return_value;
}

124
src/parser.cpp
View File

@ -1882,36 +1882,6 @@ static AstNode *ast_parse_switch_expr(ParseContext *pc, size_t *token_index, boo
}
}
static bool statement_has_block_body(AstNode *node) {
switch (node->type) {
case NodeTypeIfBoolExpr:
if (node->data.if_bool_expr.else_node)
return statement_has_block_body(node->data.if_bool_expr.else_node);
return node->data.if_bool_expr.then_block->type == NodeTypeBlock;
case NodeTypeIfVarExpr:
if (node->data.if_var_expr.else_node)
return statement_has_block_body(node->data.if_var_expr.else_node);
return node->data.if_var_expr.then_block->type == NodeTypeBlock;
case NodeTypeTryExpr:
if (node->data.try_expr.else_node)
return statement_has_block_body(node->data.try_expr.else_node);
return node->data.try_expr.then_node->type == NodeTypeBlock;
case NodeTypeWhileExpr:
return node->data.while_expr.body->type == NodeTypeBlock;
case NodeTypeForExpr:
return node->data.for_expr.body->type == NodeTypeBlock;
case NodeTypeSwitchExpr:
case NodeTypeBlock:
return true;
case NodeTypeCompTime:
return node->data.comptime_expr.expr->type == NodeTypeBlock;
case NodeTypeDefer:
return node->data.defer.expr->type == NodeTypeBlock;
default:
return false;
}
}
/*
BlockExpression(body) = Block | IfExpression(body) | TryExpression(body) | WhileExpression(body) | ForExpression(body) | SwitchExpression | CompTimeExpression(body)
*/
@ -2124,9 +2094,35 @@ static AstNode *ast_parse_label(ParseContext *pc, size_t *token_index, bool mand
return node;
}
static AstNode *ast_create_void_expr(ParseContext *pc, Token *token) {
AstNode *node = ast_create_node(pc, NodeTypeBlock, token);
return node;
static bool statement_terminates_without_semicolon(AstNode *node) {
switch (node->type) {
case NodeTypeIfBoolExpr:
if (node->data.if_bool_expr.else_node)
return statement_terminates_without_semicolon(node->data.if_bool_expr.else_node);
return node->data.if_bool_expr.then_block->type == NodeTypeBlock;
case NodeTypeIfVarExpr:
if (node->data.if_var_expr.else_node)
return statement_terminates_without_semicolon(node->data.if_var_expr.else_node);
return node->data.if_var_expr.then_block->type == NodeTypeBlock;
case NodeTypeTryExpr:
if (node->data.try_expr.else_node)
return statement_terminates_without_semicolon(node->data.try_expr.else_node);
return node->data.try_expr.then_node->type == NodeTypeBlock;
case NodeTypeWhileExpr:
return node->data.while_expr.body->type == NodeTypeBlock;
case NodeTypeForExpr:
return node->data.for_expr.body->type == NodeTypeBlock;
case NodeTypeCompTime:
return node->data.comptime_expr.expr->type == NodeTypeBlock;
case NodeTypeDefer:
return node->data.defer.expr->type == NodeTypeBlock;
case NodeTypeSwitchExpr:
case NodeTypeBlock:
case NodeTypeLabel:
return true;
default:
return false;
}
}
/*
@ -2149,56 +2145,36 @@ static AstNode *ast_parse_block(ParseContext *pc, size_t *token_index, bool mand
for (;;) {
AstNode *statement_node = ast_parse_label(pc, token_index, false);
bool need_implicit_final_void_statement = false;
if (!statement_node)
statement_node = ast_parse_variable_declaration_expr(pc, token_index, false, VisibModPrivate);
if (!statement_node)
statement_node = ast_parse_defer_expr(pc, token_index);
if (!statement_node)
statement_node = ast_parse_block_expr(pc, token_index, false);
if (!statement_node)
statement_node = ast_parse_expression(pc, token_index, false);
bool semicolon_expected = true;
if (statement_node) {
// label
semicolon_expected = false;
// if a label is the last thing in a block, add a void statement.
need_implicit_final_void_statement = true;
} else {
statement_node = ast_parse_variable_declaration_expr(pc, token_index, false, VisibModPrivate);
if (!statement_node) {
statement_node = ast_parse_defer_expr(pc, token_index);
if (statement_node) {
// defer
if (statement_has_block_body(statement_node)) {
// don't let defer be the last statement in a block
need_implicit_final_void_statement = true;
semicolon_expected = false;
} else {
// defer without a block body requires a semicolon
Token *token = &pc->tokens->at(*token_index);
ast_expect_token(pc, token, TokenIdSemicolon);
}
} else {
statement_node = ast_parse_block_expr(pc, token_index, false);
if (statement_node) {
// block expr
if (statement_has_block_body(statement_node))
semicolon_expected = false;
} else {
statement_node = ast_parse_expression(pc, token_index, false);
if (!statement_node) {
// no statement.
// final semicolon means add a void statement.
need_implicit_final_void_statement = true;
}
}
node->data.block.statements.append(statement_node);
if (statement_terminates_without_semicolon(statement_node)) {
semicolon_expected = false;
} else {
if (statement_node->type == NodeTypeDefer) {
// defer without a block body requires a semicolon
Token *token = &pc->tokens->at(*token_index);
ast_expect_token(pc, token, TokenIdSemicolon);
}
}
}
if (statement_node)
node->data.block.statements.append(statement_node);
node->data.block.last_statement_is_result_expression = statement_node && !(
statement_node->type == NodeTypeLabel ||
statement_node->type == NodeTypeDefer);
last_token = &pc->tokens->at(*token_index);
if (last_token->id == TokenIdRBrace) {
*token_index += 1;
if (node->data.block.statements.length > 0 && need_implicit_final_void_statement) {
node->data.block.statements.append(ast_create_void_expr(pc, last_token));
}
return node;
} else if (!semicolon_expected) {
continue;