⚡️ Faster initialization of string with faster slices (#5388)

**Description**

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justifying the need for this PR -->

When initializing the `string` arbitrary, we first check what are the
known-to-be-vulnerable-strings that we could possibly generate for this
instance.

As such we need to take any known-to-be-vulnerable-string and check if
it could have been generated by the string builder we are planning to
build. This operation is pretty costly as it implies a backtracking
algorithm possibly failing and retrying multiple times.

The change introduced by this PR reduces the overhead linked to this
computation by dropping part of the operations that were done twice.

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**Advanced**

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- [x] Category: ⚡️ Improve performance
- [x] Impacts: Faster init of string arbitrary

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<!-- * 🐛 Fix a bug -->
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<!-- * ⚡️ Improve performance -->
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.changeset/swift-dancers-drum.md

@@ -0,0 +1,5 @@
+---
+"fast-check": minor
+---
+
+⚡️ Faster initialization of `string` with faster slices

packages/fast-check/src/arbitrary/_internals/helpers/SlicesForStringBuilder.ts

@@ -1,5 +1,8 @@
 import type { Arbitrary } from '../../../check/arbitrary/definition/Arbitrary';
 import { safePush } from '../../../utils/globals';
+import type { StringSharedConstraints } from '../../_shared/StringSharedConstraints';
+import { patternsToStringUnmapperIsValidLength } from '../mappers/PatternsToString';
+import { tokenizeString } from './TokenizeString';
 
 const dangerousStrings = [
   // Default attributes on raw Object (from ({}).*)
@@ -30,7 +33,7 @@ const dangerousStrings = [
 ];
 
 /** @internal */
-function computeCandidateString(
+function computeCandidateStringLegacy(
   dangerous: string,
   charArbitrary: Arbitrary<string>,
   stringSplitter: (value: string) => string[],
@@ -53,16 +56,31 @@ function computeCandidateString(
 }
 
 /** @internal */
-export function createSlicesForString(
+export function createSlicesForStringLegacy(
   charArbitrary: Arbitrary<string>,
   stringSplitter: (value: string) => string[],
 ): string[][] {
   const slicesForString: string[][] = [];
   for (const dangerous of dangerousStrings) {
-    const candidate = computeCandidateString(dangerous, charArbitrary, stringSplitter);
+    const candidate = computeCandidateStringLegacy(dangerous, charArbitrary, stringSplitter);
     if (candidate !== undefined) {
       safePush(slicesForString, candidate);
     }
   }
   return slicesForString;
 }
+
+/** @internal */
+export function createSlicesForString(
+  charArbitrary: Arbitrary<string>,
+  constraints: StringSharedConstraints,
+): string[][] {
+  const slicesForString: string[][] = [];
+  for (const dangerous of dangerousStrings) {
+    const candidate = tokenizeString(charArbitrary, dangerous);
+    if (candidate !== undefined && patternsToStringUnmapperIsValidLength(candidate, constraints)) {
+      safePush(slicesForString, candidate);
+    }
+  }
+  return slicesForString;
+}

packages/fast-check/src/arbitrary/asciiString.ts

@@ -4,7 +4,7 @@ import { array } from './array';
 import { ascii } from './ascii';
 import type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 import { codePointsToStringMapper, codePointsToStringUnmapper } from './_internals/mappers/CodePointsToString';
-import { createSlicesForString } from './_internals/helpers/SlicesForStringBuilder';
+import { createSlicesForStringLegacy } from './_internals/helpers/SlicesForStringBuilder';
 export type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 
 const safeObjectAssign = Object.assign;
@@ -20,7 +20,7 @@ const safeObjectAssign = Object.assign;
  */
 export function asciiString(constraints: StringSharedConstraints = {}): Arbitrary<string> {
   const charArbitrary = ascii();
-  const experimentalCustomSlices = createSlicesForString(charArbitrary, codePointsToStringUnmapper);
+  const experimentalCustomSlices = createSlicesForStringLegacy(charArbitrary, codePointsToStringUnmapper);
   // TODO - Move back to object spreading as soon as we bump support from es2017 to es2018+
   const enrichedConstraints: ArrayConstraintsInternal<string> = safeObjectAssign(safeObjectAssign({}, constraints), {
     experimentalCustomSlices,

packages/fast-check/src/arbitrary/base64String.ts

@@ -6,7 +6,7 @@ import { MaxLengthUpperBound } from './_internals/helpers/MaxLengthFromMinLength
 import type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 import { codePointsToStringMapper, codePointsToStringUnmapper } from './_internals/mappers/CodePointsToString';
 import { stringToBase64Mapper, stringToBase64Unmapper } from './_internals/mappers/StringToBase64';
-import { createSlicesForString } from './_internals/helpers/SlicesForStringBuilder';
+import { createSlicesForStringLegacy } from './_internals/helpers/SlicesForStringBuilder';
 export type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 
 /**
@@ -31,7 +31,7 @@ function base64String(constraints: StringSharedConstraints = {}): Arbitrary<stri
   if (maxLength % 4 !== 0) throw new Error('Maximal length of base64 strings must be a multiple of 4');
 
   const charArbitrary = base64();
-  const experimentalCustomSlices = createSlicesForString(charArbitrary, codePointsToStringUnmapper);
+  const experimentalCustomSlices = createSlicesForStringLegacy(charArbitrary, codePointsToStringUnmapper);
   const enrichedConstraints: ArrayConstraintsInternal<string> = {
     minLength,
     maxLength,

packages/fast-check/src/arbitrary/fullUnicodeString.ts

@@ -4,7 +4,7 @@ import { array } from './array';
 import { fullUnicode } from './fullUnicode';
 import type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 import { codePointsToStringMapper, codePointsToStringUnmapper } from './_internals/mappers/CodePointsToString';
-import { createSlicesForString } from './_internals/helpers/SlicesForStringBuilder';
+import { createSlicesForStringLegacy } from './_internals/helpers/SlicesForStringBuilder';
 export type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 
 const safeObjectAssign = Object.assign;
@@ -20,7 +20,7 @@ const safeObjectAssign = Object.assign;
  */
 export function fullUnicodeString(constraints: StringSharedConstraints = {}): Arbitrary<string> {
   const charArbitrary = fullUnicode();
-  const experimentalCustomSlices = createSlicesForString(charArbitrary, codePointsToStringUnmapper);
+  const experimentalCustomSlices = createSlicesForStringLegacy(charArbitrary, codePointsToStringUnmapper);
   // TODO - Move back to object spreading as soon as we bump support from es2017 to es2018+
   const enrichedConstraints: ArrayConstraintsInternal<string> = safeObjectAssign(safeObjectAssign({}, constraints), {
     experimentalCustomSlices,

packages/fast-check/src/arbitrary/hexaString.ts

@@ -4,7 +4,7 @@ import { array } from './array';
 import { hexa } from './hexa';
 import type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 import { codePointsToStringMapper, codePointsToStringUnmapper } from './_internals/mappers/CodePointsToString';
-import { createSlicesForString } from './_internals/helpers/SlicesForStringBuilder';
+import { createSlicesForStringLegacy } from './_internals/helpers/SlicesForStringBuilder';
 export type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 
 const safeObjectAssign = Object.assign;
@@ -20,7 +20,7 @@ const safeObjectAssign = Object.assign;
  */
 function hexaString(constraints: StringSharedConstraints = {}): Arbitrary<string> {
   const charArbitrary = hexa();
-  const experimentalCustomSlices = createSlicesForString(charArbitrary, codePointsToStringUnmapper);
+  const experimentalCustomSlices = createSlicesForStringLegacy(charArbitrary, codePointsToStringUnmapper);
   // TODO - Move back to object spreading as soon as we bump support from es2017 to es2018+
   const enrichedConstraints: ArrayConstraintsInternal<string> = safeObjectAssign(safeObjectAssign({}, constraints), {
     experimentalCustomSlices,

packages/fast-check/src/arbitrary/string.ts

@@ -68,7 +68,7 @@ function extractUnitArbitrary(constraints: Pick<StringConstraints, 'unit'>): Arb
 export function string(constraints: StringConstraints = {}): Arbitrary<string> {
   const charArbitrary = extractUnitArbitrary(constraints);
   const unmapper = patternsToStringUnmapperFor(charArbitrary, constraints);
-  const experimentalCustomSlices = createSlicesForString(charArbitrary, unmapper);
+  const experimentalCustomSlices = createSlicesForString(charArbitrary, constraints);
   // TODO - Move back to object spreading as soon as we bump support from es2017 to es2018+
   const enrichedConstraints: ArrayConstraintsInternal<string> = safeObjectAssign(safeObjectAssign({}, constraints), {
     experimentalCustomSlices,

packages/fast-check/src/arbitrary/string16bits.ts

@@ -4,7 +4,7 @@ import { array } from './array';
 import { char16bits } from './char16bits';
 import type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 import { charsToStringMapper, charsToStringUnmapper } from './_internals/mappers/CharsToString';
-import { createSlicesForString } from './_internals/helpers/SlicesForStringBuilder';
+import { createSlicesForStringLegacy } from './_internals/helpers/SlicesForStringBuilder';
 export type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 
 const safeObjectAssign = Object.assign;
@@ -20,7 +20,7 @@ const safeObjectAssign = Object.assign;
  */
 export function string16bits(constraints: StringSharedConstraints = {}): Arbitrary<string> {
   const charArbitrary = char16bits();
-  const experimentalCustomSlices = createSlicesForString(charArbitrary, charsToStringUnmapper);
+  const experimentalCustomSlices = createSlicesForStringLegacy(charArbitrary, charsToStringUnmapper);
   // TODO - Move back to object spreading as soon as we bump support from es2017 to es2018+
   const enrichedConstraints: ArrayConstraintsInternal<string> = safeObjectAssign(safeObjectAssign({}, constraints), {
     experimentalCustomSlices,

packages/fast-check/src/arbitrary/stringOf.ts

@@ -3,7 +3,7 @@ import type { ArrayConstraintsInternal } from './array';
 import { array } from './array';
 import type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 import { patternsToStringMapper, patternsToStringUnmapperFor } from './_internals/mappers/PatternsToString';
-import { createSlicesForString } from './_internals/helpers/SlicesForStringBuilder';
+import { createSlicesForStringLegacy } from './_internals/helpers/SlicesForStringBuilder';
 export type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 
 const safeObjectAssign = Object.assign;
@@ -20,7 +20,7 @@ const safeObjectAssign = Object.assign;
  */
 export function stringOf(charArb: Arbitrary<string>, constraints: StringSharedConstraints = {}): Arbitrary<string> {
   const unmapper = patternsToStringUnmapperFor(charArb, constraints);
-  const experimentalCustomSlices = createSlicesForString(charArb, unmapper);
+  const experimentalCustomSlices = createSlicesForStringLegacy(charArb, unmapper);
   // TODO - Move back to object spreading as soon as we bump support from es2017 to es2018+
   const enrichedConstraints: ArrayConstraintsInternal<string> = safeObjectAssign(safeObjectAssign({}, constraints), {
     experimentalCustomSlices,

packages/fast-check/src/arbitrary/unicodeString.ts

@@ -4,7 +4,7 @@ import { array } from './array';
 import { unicode } from './unicode';
 import type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 import { codePointsToStringMapper, codePointsToStringUnmapper } from './_internals/mappers/CodePointsToString';
-import { createSlicesForString } from './_internals/helpers/SlicesForStringBuilder';
+import { createSlicesForStringLegacy } from './_internals/helpers/SlicesForStringBuilder';
 export type { StringSharedConstraints } from './_shared/StringSharedConstraints';
 
 const safeObjectAssign = Object.assign;
@@ -20,7 +20,7 @@ const safeObjectAssign = Object.assign;
  */
 export function unicodeString(constraints: StringSharedConstraints = {}): Arbitrary<string> {
   const charArbitrary = unicode();
-  const experimentalCustomSlices = createSlicesForString(charArbitrary, codePointsToStringUnmapper);
+  const experimentalCustomSlices = createSlicesForStringLegacy(charArbitrary, codePointsToStringUnmapper);
   // TODO - Move back to object spreading as soon as we bump support from es2017 to es2018+
   const enrichedConstraints: ArrayConstraintsInternal<string> = safeObjectAssign(safeObjectAssign({}, constraints), {
     experimentalCustomSlices,