mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Richard Smith
1ea123cd94
This follows the same structure as `if` expressions, except that no result value is needed. Semantics IR building for code blocks is also added. Rather than popping all the node stack entries we push for statements within a code block, change statements and declarations to not push themselves onto the stack. We're not notionally performing work recursively within prior statements, and we don't need their value for anything, so it seems cleaner to not push them. This also allows statements and declarations to determine what syntactic context they're in by peeking at the top of the stack, though that's not used in this patch.
89 lines
3.4 KiB
C++
89 lines
3.4 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/semantics/semantics_context.h"
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#include "toolchain/semantics/semantics_node.h"
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namespace Carbon {
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auto SemanticsHandleIfConditionStart(SemanticsContext& /*context*/,
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ParseTree::Node /*parse_node*/) -> bool {
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return true;
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}
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auto SemanticsHandleIfCondition(SemanticsContext& context,
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ParseTree::Node parse_node) -> bool {
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// Convert the condition to `bool`.
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auto cond_value_id = context.node_stack().Pop<SemanticsNodeId>();
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cond_value_id = context.ImplicitAsBool(parse_node, cond_value_id);
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// Create the else block and the then block, and branch to the right one. If
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// there is no `else`, the then block will terminate with a branch to the
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// else block, which will be reused as the resumption block.
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auto if_block_id = context.node_block_stack().PopForAdd();
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auto else_block_id = context.node_block_stack().PushForAdd();
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auto then_block_id = context.node_block_stack().PushForAdd();
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// Branch to the appropriate block.
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context.AddNodeToBlock(
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if_block_id,
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SemanticsNode::BranchIf::Make(parse_node, then_block_id, cond_value_id));
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context.AddNodeToBlock(
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if_block_id, SemanticsNode::Branch::Make(parse_node, else_block_id));
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context.node_stack().Push(parse_node);
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return true;
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}
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auto SemanticsHandleIfStatementElse(SemanticsContext& context,
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ParseTree::Node parse_node) -> bool {
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context.node_stack().PopAndDiscardSoloParseNode(ParseNodeKind::IfCondition);
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// Switch to emitting the else block.
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auto then_block_id = context.node_block_stack().PopForAdd();
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context.node_stack().Push(parse_node, then_block_id);
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return true;
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}
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auto SemanticsHandleIfStatement(SemanticsContext& context,
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ParseTree::Node parse_node) -> bool {
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// Either the then or else block, depending on whether there's an `else` node
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// on the top of the node stack.
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auto sub_block_id = context.node_block_stack().PopForAdd();
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switch (auto kind = context.parse_tree().node_kind(
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context.node_stack().PeekParseNode())) {
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case ParseNodeKind::IfCondition: {
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// Branch from then block to else block.
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context.node_stack().PopAndDiscardSoloParseNode(
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ParseNodeKind::IfCondition);
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context.AddNodeToBlock(
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sub_block_id,
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SemanticsNode::Branch::Make(parse_node,
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context.node_block_stack().PeekForAdd()));
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break;
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}
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case ParseNodeKind::IfStatementElse: {
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// Branch from the then and else blocks to a new resumption block.
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auto then_block_id = context.node_stack().Pop<SemanticsNodeBlockId>(
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ParseNodeKind::IfStatementElse);
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auto resume_block_id = context.node_block_stack().PushForAdd();
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context.AddNodeToBlock(then_block_id, SemanticsNode::Branch::Make(
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parse_node, resume_block_id));
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context.AddNodeToBlock(sub_block_id, SemanticsNode::Branch::Make(
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parse_node, resume_block_id));
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break;
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}
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default: {
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CARBON_FATAL() << "Unexpected parse node at start of `if`: " << kind;
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}
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}
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return true;
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}
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} // namespace Carbon
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