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This change introduces sem::CompoundStatement, a new base class for statements that can hold other statements. sem::BlockStatements now derives from sem::CompoundStatement, and this change introduces the following new CompoundStatements: * `sem::IfStatement` * `sem::ElseStatement` * `sem::ForLoopStatement` * `sem::LoopStatement` * `sem::SwitchStatement`. These new CompoundStatements are now inserted into the semantic tree as now documented in `docs/compound_statements.md`. The `sem::BlockStatement::FindFirstParent()` methods have been moved down to `sem::Statement`. The `Resolver::BlockScope()` method has been replaced with `Resolver::Scope()` which now maintains the `current_statement_`, `current_compound_statement_ ` and `current_block_`. This simplifies statement nesting. The most significant change in behavior is that statements now always have a parent, so calling Block() on the initializer or continuing of a for-loop statement will now return the BlockStatement that holds the for-loop. Before this would return nullptr. Fixed: tint:979 Change-Id: I90e38fd719da2a281ed9210e975ab96171cb6842 Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/57707 Kokoro: Kokoro <noreply+kokoro@google.com> Commit-Queue: Ben Clayton <bclayton@google.com> Reviewed-by: James Price <jrprice@google.com>
1.6 KiB
1.6 KiB
Compound Statements
Compound statements are statements that can hold other statements.
This document maps the WGSL compound statements to their semantic tree representations.
if statement
WGSL:
if (condition_a) {
statement_a;
} else if (condition_b) {
statement_b;
} else {
statement_c;
}
Semantic tree:
sem::IfStatement {
condition_a
sem::BlockStatement {
statement_a
}
sem::ElseStatement {
condition_b
sem::BlockStatement {
statement_b
}
}
sem::ElseStatement {
sem::BlockStatement {
statement_c
}
}
}
for loop
WGSL:
for (initializer; condition; continuing) {
statement;
}
Semantic tree:
sem::ForLoopStatement {
sem::Statement initializer
sem::Expression condition
sem::Statement continuing
sem::LoopBlockStatement {
sem::Statement statement
}
}
loop
WGSL:
loop (condition) {
statement_a;
continuing {
statement_b;
}
}
Semantic tree:
sem::LoopStatement {
sem::Expression condition
sem::LoopBlockStatement {
sem::Statement statement_a
sem::LoopContinuingBlockStatement {
sem::Statement statement_b
}
}
}
switch statement
WGSL:
switch (condition) {
case literal_a, literal_b: {
statement_a;
}
default {
statement_b;
}
}
Semantic tree:
sem::SwitchStatement {
sem::Expression condition
sem::SwitchCaseBlockStatement {
sem::Statement statement_a
}
sem::SwitchCaseBlockStatement {
sem::Statement statement_b
}
}