Add new query for getting available variables (#52)

* Add new query for getting available variables

* use array for findAllPreviousVariables

src/lang/queryAst.ts

@@ -1,6 +1,7 @@
-import { PathToNode } from './executor'
+import { PathToNode, ProgramMemory } from './executor'
 import { Range } from '../useStore'
 import { Program } from './abstractSyntaxTree'
+import { splitPathAtLastIndex } from './modifyAst'
 
 export function getNodeFromPath<T>(
   node: Program,
@@ -133,3 +134,43 @@ export function getNodePathFromSourceRange(
   }
   return path
 }
+
+interface PrevVariable<T> {
+  key: string
+  value: T
+}
+
+export function findAllPreviousVariables(
+  ast: Program,
+  programMemory: ProgramMemory,
+  sourceRange: Range,
+  type: 'number' | 'string' = 'number'
+): {
+  variables: PrevVariable<typeof type extends 'number' ? number : string>[]
+  bodyPath: PathToNode
+  insertIndex: number
+} {
+  const path = getNodePathFromSourceRange(ast, sourceRange)
+  const { path: pathToDec } = getNodeFromPath(ast, path, 'VariableDeclaration')
+  const { index: insertIndex, path: bodyPath } = splitPathAtLastIndex(pathToDec)
+
+  const { node: bodyItems } = getNodeFromPath<Program['body']>(ast, bodyPath)
+
+  const variables: PrevVariable<any>[] = []
+  bodyItems.forEach((item) => {
+    if (item.type !== 'VariableDeclaration' || item.end > sourceRange[0]) return
+    const varName = item.declarations[0].id.name
+    const varValue = programMemory?.root[varName]
+    if (typeof varValue?.value !== type) return
+    variables.push({
+      key: varName,
+      value: varValue.value,
+    })
+  })
+
+  return {
+    insertIndex,
+    bodyPath: bodyPath,
+    variables,
+  }
+}