optimize out unnecessary recursion

maxdeliso · Jun 30, 2024 · e0854f4 · e0854f4
1 parent f376aae
commit e0854f4
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Showing 3 changed files with 16 additions and 29 deletions.
diff --git a/lib/parser/recursiveDescentBuffer.ts b/lib/parser/recursiveDescentBuffer.ts
@@ -58,8 +58,4 @@ export class RecursiveDescentBuffer {
     this.consume()
     return next
   }
-
-  peelRemaining (): RecursiveDescentBuffer {
-    return new RecursiveDescentBuffer(this.buf.slice(this.idx))
-  }
 }
diff --git a/lib/parser/typed.ts b/lib/parser/typed.ts
@@ -63,17 +63,6 @@ function parseTypeInternal (rdb: RecursiveDescentBuffer): [string, Type] {
     }
   }
 }
-function parseLambdaInternal (rdb: RecursiveDescentBuffer):
-[string, TypedLambda] {
-  rdb.matchCh('λ')
-  const varLit = rdb.parseVariable()
-  rdb.matchCh(':')
-  const [typeLit, ty] = parseTypeInternal(rdb)
-  rdb.matchCh('.')
-  const [bodyLit, term] = parseTypedLambdaInternal(rdb.peelRemaining())
-  rdb.consumeN(bodyLit.length)
-  return [`λ${varLit}:${typeLit}.${bodyLit}`, mkTypedAbs(varLit, ty, term)]
-}
 
 function parseTypedLambdaInternal (rdb: RecursiveDescentBuffer):
 [string, TypedLambda] {
@@ -84,7 +73,16 @@ function parseTypedLambdaInternal (rdb: RecursiveDescentBuffer):
     let nextTerm: TypedLambda
 
     if (rdb.peek() === 'λ') {
-      const [lambdaLit, lambdaTerm] = parseLambdaInternal(rdb)
+      rdb.matchCh('λ')
+      const varLit = rdb.parseVariable()
+      rdb.matchCh(':')
+      const [typeLit, ty] = parseTypeInternal(rdb)
+      rdb.matchCh('.')
+      const [bodyLit, term] = parseTypedLambdaInternal(rdb)
+      const [lambdaLit, lambdaTerm] = [
+        `λ${varLit}:${typeLit}.${bodyLit}`,
+        mkTypedAbs(varLit, ty, term)
+      ]
       nextTerm = lambdaTerm
       resultStr += lambdaLit
     } else {

diff --git a/lib/parser/untyped.ts b/lib/parser/untyped.ts
@@ -17,9 +17,12 @@ function parseUntypedLambdaInternal (rdb: RecursiveDescentBuffer):
     let nextTerm: UntypedLambda | undefined
 
     if (rdb.peek() === 'λ') {
-      const [lambdaLit, lambdaTerm] = parseUntypedLambda(rdb)
-      resultStr += lambdaLit
-      nextTerm = lambdaTerm
+      rdb.matchCh('λ')
+      const varLit = rdb.parseVariable()
+      rdb.matchCh('.')
+      const [bodyLit, term] = parseUntypedLambdaInternal(rdb)
+      resultStr += `λ${varLit}.${bodyLit}`
+      nextTerm = mkUntypedAbs(varLit, term)
     } else if (rdb.peek() === '(') {
       rdb.matchLP()
       const [lit1, t1] = parseUntypedLambdaInternal(rdb)
@@ -49,13 +52,3 @@ function parseUntypedLambdaInternal (rdb: RecursiveDescentBuffer):
 
   return [resultStr, resultExpr]
 }
-
-function parseUntypedLambda (rdb: RecursiveDescentBuffer):
-[string, UntypedLambda] {
-  rdb.matchCh('λ')
-  const varLit = rdb.parseVariable()
-  rdb.matchCh('.')
-  const [bodyLit, term] = parseLambda(rdb.peelRemaining().buf)
-  rdb.consumeN(bodyLit.length)
-  return [`λ${varLit}.${bodyLit}`, mkUntypedAbs(varLit, term)]
-}