From a7dfb98e4b0aa36c645c157974d2f8d661031c16 Mon Sep 17 00:00:00 2001
From: Benjie Gillam <benjie@jemjie.com>
Date: Thu, 6 Mar 2025 09:42:51 +0000
Subject: [PATCH 1/2] String accumulation is faster than array join

---
 index.js | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/index.js b/index.js
index aa93257..bc168ff 100644
--- a/index.js
+++ b/index.js
@@ -20,6 +20,14 @@ const NULL_STRING = 'NULL'
 function makeParseArrayWithTransform (transform) {
   const haveTransform = transform != null
   return function parseArray (str) {
+    const rbraceIndex = str.length - 1
+    if (rbraceIndex === 1) {
+      return []
+    }
+    if (str[rbraceIndex] !== RBRACE) {
+      throw new Error('Invalid array text - must end with }')
+    }
+
     // If starts with `[`, it is specifying the index boundas. Skip past first `=`.
     let position = 0
     if (str[position] === LBRACKET) {
@@ -29,17 +37,12 @@ function makeParseArrayWithTransform (transform) {
     if (str[position++] !== LBRACE) {
       throw new Error('Invalid array text - must start with {')
     }
-    const rbraceIndex = str.length - 1
-    if (str[rbraceIndex] !== RBRACE) {
-      throw new Error('Invalid array text - must end with }')
-    }
     const output = []
     let current = output
     const stack = []
 
     let currentStringStart = position
-    const currentStringParts = []
-    let hasStringParts = false
+    let currentString = null
     let expectValue = true
 
     for (; position < rbraceIndex; ++position) {
@@ -56,8 +59,11 @@ function makeParseArrayWithTransform (transform) {
         while (backSlash !== -1 && backSlash < dquot) {
           position = backSlash
           const part = str.slice(currentStringStart, position)
-          currentStringParts.push(part)
-          hasStringParts = true
+          if (currentString === null) {
+            currentString = part
+          } else {
+            currentString += part
+          }
           currentStringStart = ++position
           if (dquot === position++) {
             // This was an escaped doublequote; find the next one!
@@ -68,13 +74,12 @@ function makeParseArrayWithTransform (transform) {
         }
         position = dquot
         const part = str.slice(currentStringStart, position)
-        if (hasStringParts) {
-          const final = currentStringParts.join('') + part
-          current.push(haveTransform ? transform(final) : final)
-          currentStringParts.length = 0
-          hasStringParts = false
-        } else {
+        if (currentString === null) {
           current.push(haveTransform ? transform(part) : part)
+        } else {
+          currentString += part
+          current.push(haveTransform ? transform(currentString) : currentString)
+          currentString = null
         }
         expectValue = false
       } else if (char === LBRACE) {

From 0f5cca5b4117869487eb3176df63a626107346ef Mon Sep 17 00:00:00 2001
From: Benjie Gillam <benjie@jemjie.com>
Date: Thu, 6 Mar 2025 10:03:05 +0000
Subject: [PATCH 2/2] No measurable performance difference and simpler code

---
 index.js | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/index.js b/index.js
index bc168ff..3383d2b 100644
--- a/index.js
+++ b/index.js
@@ -42,7 +42,7 @@ function makeParseArrayWithTransform (transform) {
     const stack = []
 
     let currentStringStart = position
-    let currentString = null
+    let currentString = ''
     let expectValue = true
 
     for (; position < rbraceIndex; ++position) {
@@ -59,11 +59,7 @@ function makeParseArrayWithTransform (transform) {
         while (backSlash !== -1 && backSlash < dquot) {
           position = backSlash
           const part = str.slice(currentStringStart, position)
-          if (currentString === null) {
-            currentString = part
-          } else {
-            currentString += part
-          }
+          currentString += part
           currentStringStart = ++position
           if (dquot === position++) {
             // This was an escaped doublequote; find the next one!
@@ -74,13 +70,9 @@ function makeParseArrayWithTransform (transform) {
         }
         position = dquot
         const part = str.slice(currentStringStart, position)
-        if (currentString === null) {
-          current.push(haveTransform ? transform(part) : part)
-        } else {
-          currentString += part
-          current.push(haveTransform ? transform(currentString) : currentString)
-          currentString = null
-        }
+        currentString += part
+        current.push(haveTransform ? transform(currentString) : currentString)
+        currentString = ''
         expectValue = false
       } else if (char === LBRACE) {
         const newArray = []