rewriteExprsInFunc()

Syntax

function rewriteExprsInFunc(f: FuncDecl, rewrite: (e: Expr) => Expr): FuncDecl

Parameters

f FuncDecl

The function whose body is rewritten.

rewrite (e: Expr) => Expr

Called once per expression. Return the expression unchanged to keep it, or a new expression to replace it.

Return value

FuncDecl

A copy of f with the rewritten body, or f itself when no expression changed.

Description

The walk visits every statement and expression shape in the body. Each expression is passed to rewrite after its children have been rewritten, and whatever rewrite returns is taken as finished output: it is not walked again.

Object identity is preserved wherever possible. A subtree that rewrite leaves alone comes back as the original object, and f itself is returned when nothing in the body changed. An expression object that appears at several places in the body is rewritten once, and the same new object is used at every occurrence, so passes that correlate a variable’s declaration, assignments and reads by object identity keep working on the result.

Examples

// Replace every literal `0` with `1`.
const g = rewriteExprsInFunc(f, (e) =>
  e.op === 'lit' && e.value === 0 ? { ...e, value: 1 } : e,
)

Source

src/core/passes/rename-varrefs.ts, line 71, at commit 26de7be8