module call context

.changeset/stupid-flowers-sin.md

@@ -0,0 +1,8 @@
+---
+"@getlang/parser": minor
+"@getlang/utils": minor
+"@getlang/get": minor
+"@getlang/lib": minor
+---
+
+module call context

biome.json

@@ -33,7 +33,13 @@
       "style": {
         "noUselessElse": "off",
         "noNonNullAssertion": "off",
-        "useBlockStatements": "error"
+        "useBlockStatements": "error",
+        "useImportType": {
+          "level": "error",
+          "options": {
+            "style": "separatedType"
+          }
+        }
       }
     }
   },

packages/get/src/context.ts

@@ -0,0 +1,47 @@
+import type { CExpr, Expr } from '@getlang/parser/ast'
+import type { RootScope } from '@getlang/parser/scope'
+import type { TypeInfo } from '@getlang/parser/typeinfo'
+import { Type } from '@getlang/parser/typeinfo'
+import type { MaybePromise } from '@getlang/utils'
+import { NullSelection } from '@getlang/utils'
+import { assert } from './value.js'
+
+type Contextual = { value: any; typeInfo: TypeInfo }
+
+export async function withContext(
+  scope: RootScope<any>,
+  node: CExpr,
+  visit: (node: Expr) => MaybePromise<any>,
+  cb: (ctx?: Contextual) => MaybePromise<any>,
+): Promise<any> {
+  async function unwrap(
+    context: Contextual | undefined,
+    cb: (ctx?: Contextual) => MaybePromise<any>,
+  ): Promise<any> {
+    if (context?.typeInfo.type === Type.List) {
+      const list = []
+      for (const item of context.value) {
+        const itemCtx = { value: item, typeInfo: context.typeInfo.of }
+        list.push(await unwrap(itemCtx, cb))
+      }
+      return list
+    }
+
+    context && scope.pushContext(context.value)
+    const value = await cb(context)
+    context && scope.popContext()
+    return value
+  }
+
+  let context: Contextual | undefined
+  if (node.context) {
+    let value = await visit(node.context)
+    const optional = node.typeInfo.type === Type.Maybe
+    value = optional ? value : assert(value)
+    if (value instanceof NullSelection) {
+      return value
+    }
+    context = { value, typeInfo: node.context.typeInfo }
+  }
+  return unwrap(context, cb)
+}