add visitInParallel as the BREAK types were not compatible (#15)

* this adds visit in parallel as the BREAK types were not compatible

* remove unsupported syntax

alias/language/visitor.mjs

···
-export { getEnterLeaveForKind, getVisitFn, visitInParallel } from 'graphql/language/visitor';
+import { BREAK, Kind } from '@0no-co/graphql.web';
+import { getEnterLeaveForKind } from 'graphql/language/visitor';
+
+export { getEnterLeaveForKind, getVisitFn } from 'graphql/language/visitor';
+export { BREAK, visit, Kind } from '@0no-co/graphql.web';
+
+export function visitInParallel(visitors) {
+  const skipping = new Array(visitors.length).fill(null);
+  const mergedVisitor = Object.create(null);
+
+  for (const kind of Object.values(Kind)) {
+    let hasVisitor = false;
+    const enterList = new Array(visitors.length).fill(undefined);
+    const leaveList = new Array(visitors.length).fill(undefined);
+
+    for (let i = 0; i < visitors.length; ++i) {
+      const { enter, leave } = getEnterLeaveForKind(visitors[i], kind);
+      hasVisitor = hasVisitor || enter != null || leave != null;
+      enterList[i] = enter;
+      leaveList[i] = leave;
+    }
+
+    if (!hasVisitor) {
+      continue;
+    }
+
+    const mergedEnterLeave = {
+      enter(...args) {
+        const node = args[0];
+        for (let i = 0; i < visitors.length; i++) {
+          if (skipping[i] === null) {
+            const result = enterList[i] && enterList[i].apply(visitors[i], args);
+            if (result === false) {
+              skipping[i] = node;
+            } else if (result === BREAK) {
+              skipping[i] = BREAK;
+            } else if (result !== undefined) {
+              return result;
+            }
+          }
+        }
+      },
+      leave(...args) {
+        const node = args[0];
+        for (let i = 0; i < visitors.length; i++) {
+          if (skipping[i] === null) {
+            const result = leaveList[i] && leaveList[i].apply(visitors[i], args);
+            if (result === BREAK) {
+              skipping[i] = BREAK;
+            } else if (result !== undefined && result !== false) {
+              return result;
+            }
+          } else if (skipping[i] === node) {
+            skipping[i] = null;
+          }
+        }
+      },
+    };
 
-export { BREAK, visit } from '@0no-co/graphql.web';
+    mergedVisitor[kind] = mergedEnterLeave;
+  }
+
+  return mergedVisitor;
+}