Enable the Code Editor, with new apply-text-edits algo. (#9055)

- Fix the UI problems with our CodeMirror integration (Fixed view stability; Fixed a focus bug; Fixed errors caused by diagnostics range exceptions; Fixed linter invalidation--see https://discuss.codemirror.net/t/problem-trying-to-force-linting/5823; Implemented edit-coalescing for performance).
- Introduce an algorithm for applying text edits to an AST. Compared to the GUI1 approach, the new algorithm supports deeper identity-stability for expressions (which is important for subexpression metadata and Y.Js sync), as well as reordered-subtree identification.
- Enable the code editor.

app/gui2/mock/index.ts

@@ -67,7 +67,7 @@ export function projectStore() {
   const mod = projectStore.projectModel.createNewModule('Main.enso')
   mod.doc.ydoc.emit('load', [])
   const syncModule = new Ast.MutableModule(mod.doc.ydoc)
-  mod.transact(() => {
+  syncModule.transact(() => {
     const root = Ast.parseBlock('main =\n', syncModule)
     syncModule.replaceRoot(root)
   })

app/gui2/shared/ast/debug.ts

@@ -0,0 +1,22 @@
+import { Ast } from './tree'
+
+/// Returns a GraphViz graph illustrating parent/child relationships in the given subtree.
+export function graphParentPointers(ast: Ast) {
+  const sanitize = (id: string) => id.replace('ast:', '').replace(/[^A-Za-z0-9]/g, '')
+  const parentToChild = new Array<{ parent: string; child: string }>()
+  const childToParent = new Array<{ child: string; parent: string }>()
+  ast.visitRecursiveAst((ast) => {
+    for (const child of ast.children()) {
+      if (child instanceof Ast)
+        parentToChild.push({ child: sanitize(child.id), parent: sanitize(ast.id) })
+    }
+    const parent = ast.parentId
+    if (parent) childToParent.push({ child: sanitize(ast.id), parent: sanitize(parent) })
+  })
+  let result = 'digraph parentPointers {\n'
+  for (const { parent, child } of parentToChild) result += `${parent} -> ${child};\n`
+  for (const { child, parent } of childToParent)
+    result += `${child} -> ${parent} [weight=0; color=red; style=dotted];\n`
+  result += '}\n'
+  return result
+}

app/gui2/shared/ast/ffi.ts

@@ -1,6 +1,16 @@
+import { createXXHash128 } from 'hash-wasm'
 import init, { is_ident_or_operator, parse, parse_doc_to_json } from '../../rust-ffi/pkg/rust_ffi'
+import { assertDefined } from '../util/assert'
 import { isNode } from '../util/detect'
 
+let xxHasher128: Awaited<ReturnType<typeof createXXHash128>> | undefined
+export function xxHash128(input: string) {
+  assertDefined(xxHasher128, 'Module should have been loaded with `initializeFFI`.')
+  xxHasher128.init()
+  xxHasher128.update(input)
+  return xxHasher128.digest()
+}
+
 export async function initializeFFI(path?: string | undefined) {
   if (isNode) {
     const fs = await import('node:fs/promises')
@@ -9,6 +19,7 @@ export async function initializeFFI(path?: string | undefined) {
   } else {
     await init()
   }
+  xxHasher128 = await createXXHash128()
 }
 
 // TODO[ao]: We cannot to that, because the ffi is used by cjs modules.

app/gui2/shared/ast/index.ts

@@ -40,7 +40,7 @@ export function parentId(ast: Ast): AstId | undefined {
 export function subtrees(module: Module, ids: Iterable<AstId>) {
   const subtrees = new Set<AstId>()
   for (const id of ids) {
-    let ast = module.get(id)
+    let ast = module.tryGet(id)
     while (ast != null && !subtrees.has(ast.id)) {
       subtrees.add(ast.id)
       ast = ast.parent()
@@ -50,10 +50,10 @@ export function subtrees(module: Module, ids: Iterable<AstId>) {
 }
 
 /** Returns the IDs of the ASTs that are not descendants of any others in the given set. */
-export function subtreeRoots(module: Module, ids: Set<AstId>) {
-  const roots = new Array<AstId>()
+export function subtreeRoots(module: Module, ids: Set<AstId>): Set<AstId> {
+  const roots = new Set<AstId>()
   for (const id of ids) {
-    const astInModule = module.get(id)
+    const astInModule = module.tryGet(id)
     if (!astInModule) continue
     let ast = astInModule.parent()
     let hasParentInSet
@@ -64,7 +64,7 @@ export function subtreeRoots(module: Module, ids: Set<AstId>) {
       }
       ast = ast.parent()
     }
-    if (!hasParentInSet) roots.push(id)
+    if (!hasParentInSet) roots.add(id)
   }
   return roots
 }