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[doc] explain how case clauses with multiple selectors are supported

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teoxoy
2022-11-17 18:34:54 +01:00
committed by Jim Blandy
parent f36adeefaa
commit 63e85b4b15
1 changed files with 16 additions and 0 deletions
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16
src/lib.rs
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@@ -1466,6 +1466,22 @@ pub enum Statement {
reject: Block,
},
/// Conditionally executes one of multiple blocks, based on the value of the selector.
///
/// Each case must have a distinct [`value`], exactly one of which must be
/// [`Default`]. The `Default` may appear at any position, and covers all
/// values not explicitly appearing in other cases. A `Default` appearing in
/// the midst of the list of cases does not shadow the cases that follow.
///
/// Some backend languages don't support fallthrough (HLSL due to FXC,
/// WGSL), and may translate fallthrough cases in the IR by duplicating
/// code. However, all backend languages do support cases selected by
/// multiple values, like `case 1: case 2: case 3: { ... }`. This is
/// represented in the IR as a series of fallthrough cases with empty
/// bodies, except for the last.
///
/// [`value`]: SwitchCase::value
/// [`body`]: SwitchCase::body
/// [`Default`]: SwitchValue::Default
Switch {
selector: Handle<Expression>, //int
cases: Vec<SwitchCase>,