feate: implement a basic parser for the reflected types

src/core/Dispatcher.ts

@@ -47,6 +47,12 @@ export class Dispatcher {
       // that's really possible, though.
    ) {
       console.log('Pretending to install', name, signature, '=>', returns)
+      // @ts-ignore
+      if (behavior.reflectedType) {
+         // @ts-ignore
+         console.log('  Reflected type:', behavior.reflectedType)
+         // TODO: parse the reflected type
+      }
       //TODO: implement me
    }
    installType(name: TypeName, typespec: TypeSpecification) {

src/core/parseReflectedType.ts

@@ -0,0 +1,232 @@
+export interface FunctionDef {
+  name: string,
+  signatures: Array<{
+    args: Array<{ name: string, type: string }>
+    // FIXME: remove undefined in the end
+    returns: string | undefined
+  }>
+}
+
+export interface DependencyDef extends FunctionDef {
+  aliasOf: string | undefined
+}
+
+/**
+ * Parse a reflected type coming out of TypeScript into a structured object, for example:
+ *
+ *   '<T>(dep: configDependency & { complex: ((re: number) => Complex<number>) | ((re: number, im: number) => Complex<number>); }) => (a: number) => number | Complex<number>'
+ */
+export function parseReflectedType(name: string, reflectedType: string) : { fn: FunctionDef, dependencies: Record<string, DependencyDef> } {
+  const [factoryArgs, fnArgsBlock, returns] = split(reflectedType, '=>').map(trim)
+  const args = parseArgs(fnArgsBlock)
+
+  const factoryArgsInner = findBlockContents(factoryArgs, '(', ')')
+  const depArg = split(factoryArgsInner.innerText, ':').map(trim)[1]
+  const depArgBlocks = split(depArg, '&').map(trim)
+
+  const deps = depArgBlocks
+    .filter(depArgBlock => {
+      if (depArgBlock.startsWith('{')) {
+        return true
+      } else {
+        console.error(`ERROR: Cannot parse dependency "${depArgBlock}"`)
+      }
+    })
+    .flatMap(parseDependencies)
+
+  const dependencies: Record<string, DependencyDef> = groupBy(deps, 'name')
+
+  return {
+    fn: { name, signatures: [{args, returns}] },
+    dependencies
+  }
+
+  function parseDependencies(deps: string) {
+    const inner = findBlockContents(deps, '{', '}').innerText
+    return split(inner, ';')
+      .map(trim)
+      .filter(notEmpty)
+      .map(parseDependency)
+  }
+
+  // parse a dependency like "complex: ((re: number) => Complex<number>) | ((re: number, im: number) => Complex<number>)"
+  function parseDependency(dep: string) {
+    const [name, def] = split(dep, ':').map(trim)
+
+    const { aliasOf, innerSignature } = parseAliasOf(def)
+
+    const signatures = split(innerSignature, '|')
+      .map(trim)
+      .map(stripParenthesis)
+      .map(signature => {
+        const [argsBlock, returns] = split(signature, '=>').map(trim)
+
+        if (!returns) {
+          console.warn(`ERROR: failed to find return type in '${signature}'`)
+        }
+
+        return {
+          args: parseArgs(argsBlock),
+          returns
+        }
+      })
+
+    return { name, signatures, aliasOf }
+  }
+
+  // parse args like "(re: number, im: number)"
+  function parseArgs(argsBlock: string) : Array<{name: string, type: string}> {
+    const args = findBlockContents(argsBlock, '(', ')').innerText
+
+    return split(args, ',')
+      .map(trim)
+      .map(arg => {
+        const [name, type] = split(arg, ':').map(trim)
+        return { name, type}
+      })
+  }
+
+  // parse "AliasOf<"divide", (a: Complex<T>, b: RealType<Complex<T>>) => Complex<T>>"
+  function parseAliasOf(signature: string) : { innerSignature: string, aliasOf: string | undefined } {
+    if (!signature.startsWith('AliasOf')) {
+      return {
+        innerSignature: signature,
+        aliasOf: undefined
+      }
+    }
+
+    const inner = findBlockContents(signature, '<', '>').innerText.trim()
+    const [aliasOfWithQuotes, innerSignature] = split(inner, ',').map(trim)
+    return {
+      innerSignature,
+      aliasOf: aliasOfWithQuotes.substring(1, aliasOfWithQuotes.length - 1) // remove double quotes
+    }
+  }
+
+  // remove the outer parenthesis, for example "((re: number) => Complex<number>)" returns "(re: number) => Complex<number>"
+  function stripParenthesis(text: string) : string {
+    return text.startsWith('(') && text.endsWith(')')
+      ? text.substring(1, text.length - 1)
+      : text
+  }
+}
+
+function findBlockContents(text: string, blockStart: string, blockEnd: string, startIndex = 0) : { start: number, end: number, innerText: string } | undefined {
+  let i = startIndex
+
+  while (!matchSubString(text, blockStart, i) && i < text.length) {
+    i++
+  }
+
+  if (i >= text.length) {
+    return undefined
+  }
+
+  i++
+  const start = i
+
+  while (!matchSubString(text, blockEnd, i) || matchSubString(text, '=>', i - 1)) {
+    i = skipBrackets(text, i)
+
+    i++
+  }
+
+  if (i >= text.length) {
+    return undefined
+  }
+  const end = i
+
+  return {
+    start,
+    end,
+    innerText: text.substring(start, end)
+  }
+}
+
+/**
+ * Split a string by a delimiter, but ignore all occurrences of the delimiter
+ * that are inside bracket pairs <> () [] {}
+ */
+export function split(text: string, delimiter: string) : string[] {
+  const parts: string[] = []
+
+  let i = 0
+  let start = 0
+  while (i < text.length) {
+    i = skipBrackets(text, i)
+
+    if (matchSubString(text, delimiter, i)) {
+      parts.push(text.substring(start, i))
+      i += delimiter.length
+      start = i
+    }
+
+    i++
+  }
+
+  parts.push(text.substring(start))
+
+  return parts
+}
+
+function skipBrackets(text: string, startIndex: number) : number {
+  let level = 0
+  let i = startIndex
+
+  do {
+    if (isBracketOpen(text, i)) {
+      level++
+    }
+
+    if (isBracketClose(text, i) && level > 0) {
+      level--
+    }
+
+    if (level === 0) {
+      break
+    }
+
+    i++
+  } while(i < text.length)
+
+  return i
+}
+
+function isBracketOpen(text: string, index: number) {
+  const char = text[index]
+  return char === '(' || char === '<' || char === '[' || char === '{'
+}
+
+function isBracketClose(text: string, index: number) {
+  const char = text[index]
+  // we need to take care of not matching the ">" of the operator "=>"
+  return char === ')' || (char === '>' && text[index - 1] !== '=') || char === ']' || char === '}'
+}
+
+function matchSubString(text: string, search: string, index: number) : boolean {
+  for (let i = 0; i < search.length; i++) {
+    if (text[i + index] !== search[i]) {
+      return false
+    }
+  }
+
+  return true
+}
+
+function trim(text: string) : string {
+  return text.trim()
+}
+
+function notEmpty(text: string) : boolean {
+  return text.length > 0
+}
+
+function groupBy<T>(items: T[], key: string) : Record<string, T> {
+  const obj: Record<string, T> = {}
+
+  items.forEach((item) => {
+    obj[item[key]] = item
+  })
+
+  return obj
+}

src/index.ts

@@ -1,3 +1,4 @@
+import { inspect} from 'node:util'
 import {Dispatcher} from './core/Dispatcher.js'
 import * as Specifications from './all.js'
 
@@ -5,6 +6,7 @@ export default new Dispatcher(Specifications)
 
 import {Complex} from './Complex/type.js'
 import {absquare as absquare_complex} from './Complex/arithmetic.js'
+import { parseReflectedType, split } from './core/parseReflectedType.js'
 
 const mockRealAdd = (a: number, b: number) => a+b
 const mockComplexAbsquare = (z: Complex<number>) => z.re*z.re + z.im*z.im
@@ -31,7 +33,23 @@ const sqrt = Specifications.numbers.sqrt({
 console.log('Result of sqrt(16)=', sqrt(16))
 console.log('Result of sqrt(-4)=', sqrt(-4))
 
-// Check type of the generic square implementation
-console.log('Type of sqrt (number) is', Specifications.numbers.sqrt.reflectedType)
-console.log('Type of square is', Specifications.generic.square.reflectedType)
-console.log('Type of complex square root is', Specifications.complex.sqrt.reflectedType)
+console.log()
+console.log('1) NUMBER SQRT')
+console.log('1.1) REFLECTED TYPE:', Specifications.numbers.sqrt.reflectedType)
+console.log('1.2) PARSED TYPE:', inspect(parseReflectedType('sqrt', Specifications.numbers.sqrt.reflectedType), { depth: null, colors: true }))
+
+console.log()
+console.log('2) GENERIC SQUARE')
+console.log('2.1) REFLECTED TYPE:', Specifications.generic.square.reflectedType)
+console.log('2.2) PARSED TYPE:', inspect(parseReflectedType('square', Specifications.generic.square.reflectedType), { depth: null, colors: true }))
+
+console.log()
+console.log('3) COMPLEX SQRT')
+console.log('3.1) REFLECTED TYPE:', Specifications.complex.sqrt.reflectedType)
+console.log('3.2) PARSED TYPE:', inspect(parseReflectedType('sqrt', Specifications.complex.sqrt.reflectedType), { depth: null, colors: true }))
+
+// FIXME: cleanup
+// console.log()
+// console.log('split', split('hello**world**how**are**you', '**'))
+// console.log('split', split('hello(test**world)**how**are**you', '**'))
+// console.log('split', split('<T>(dep: { multiply: (a: T, b: T) => T; }) => (z: T) => T', '=>'))