feat: add flow node type guards

src/flags.ts

@@ -21,6 +21,22 @@ function isFlagSetOnObject(obj: { flags: number }, flag: number): boolean {
  return isFlagSet(obj.flags, flag);
 }
 
+/**
+ * Test if the given node has the given `FlowFlags` set.
+ *
+ * @category Flow Nodes - Flag Utilities
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowFlagSet(flowNode, ts.FlowFlags.Referenced)) {
+ * // ...
+ * }
+ * ```
+ */
+export const isFlowFlagSet: (node: ts.Node, flag: ts.FlowFlags) => boolean =
+ isFlagSetOnObject;
+
 /**
  * Test if the given node has the given `ModifierFlags` set.
  *

src/flowNodes/index.ts

@@ -0,0 +1 @@
+export * from "./typeGuards";

src/flowNodes/typeGuards/index.ts

@@ -0,0 +1,204 @@
+import ts from "typescript";
+
+/**
+ * Test if a flow node is a `FlowStart`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowStart(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowStart`.
+ */
+export function isFlowStart(flowNode: ts.FlowNode): flowNode is ts.FlowStart {
+ return (
+ "node" in flowNode &&
+ (flowNode.node === undefined ||
+ ts.isFunctionExpression(flowNode.node) ||
+ ts.isArrowFunction(flowNode.node) ||
+ ts.isMethodDeclaration(flowNode.node) ||
+ ts.isGetAccessorDeclaration(flowNode.node) ||
+ ts.isSetAccessorDeclaration(flowNode.node))
+ );
+}
+
+/**
+ * Test if a flow node is a `FlowLabel`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowLabel(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowLabel`.
+ */
+export function isFlowLabel(flowNode: ts.FlowNode): flowNode is ts.FlowLabel {
+ return "antecedents" in flowNode && !("antecedent" in flowNode);
+}
+
+/**
+ * Test if a flow node is a `FlowAssignment`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowAssignment(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowAssignment`.
+ */
+export function isFlowAssignment(
+ flowNode: ts.FlowNode
+): flowNode is ts.FlowAssignment {
+ return (
+ "node" in flowNode &&
+ "antecedent" in flowNode &&
+ !("antecedents" in flowNode) &&
+ (ts.isExpression(flowNode.node) ||
+ ts.isVariableDeclaration(flowNode.node) ||
+ ts.isBindingElement(flowNode.node))
+ );
+}
+
+/**
+ * Test if a flow node is a `FlowCall`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowCall(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowCall`.
+ */
+export function isFlowCall(flowNode: ts.FlowNode): flowNode is ts.FlowCall {
+ return (
+ "node" in flowNode &&
+ "antecedent" in flowNode &&
+ !("antecedents" in flowNode) &&
+ ts.isCallExpression(flowNode.node)
+ );
+}
+
+/**
+ * Test if a flow node is a `FlowCondition`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowCondition(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowCondition`.
+ */
+export function isFlowCondition(
+ flowNode: ts.FlowNode
+): flowNode is ts.FlowCondition {
+ return (
+ "node" in flowNode &&
+ "antecedent" in flowNode &&
+ !("antecedents" in flowNode) &&
+ ts.isExpression(flowNode.node)
+ );
+}
+
+/**
+ * Test if a flow node is a `FlowSwitchClause`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowSwitchClause(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowSwitchClause`.
+ */
+export function isFlowSwitchClause(
+ flowNode: ts.FlowNode
+): flowNode is ts.FlowSwitchClause {
+ return (
+ "switchStatement" in flowNode &&
+ "clauseStart" in flowNode &&
+ "clauseEnd" in flowNode &&
+ "antecedent" in flowNode &&
+ !("antecedents" in flowNode) &&
+ ts.isSwitchStatement(flowNode.switchStatement)
+ );
+}
+
+/**
+ * Test if a flow node is a `FlowArrayMutation`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowArrayMutation(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowArrayMutation`.
+ */
+export function isFlowArrayMutation(
+ flowNode: ts.FlowNode
+): flowNode is ts.FlowArrayMutation {
+ return (
+ "node" in flowNode &&
+ "antecedent" in flowNode &&
+ !("antecedents" in flowNode) &&
+ (ts.isCallExpression(flowNode.node) || ts.isBinaryExpression(flowNode.node))
+ );
+}
+
+/**
+ * Test if a flow node is a `FlowReduceLabel`.
+ *
+ * @category Flow Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const flowNode: ts.FlowNode;
+ *
+ * if (isFlowReduceLabel(flowNode)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node appears to be a `FlowReduceLabel`.
+ */
+export function isFlowReduceLabel(
+ flowNode: ts.FlowNode
+): flowNode is ts.FlowReduceLabel {
+ return (
+ "target" in flowNode &&
+ "antecedents" in flowNode &&
+ "antecedent" in flowNode
+ );
+}

src/index.ts

@@ -1,6 +1,7 @@
 export * from "./comments";
 export * from "./compilerOptions";
 export * from "./flags";
+export * from "./flowNodes";
 export * from "./modifiers";
 export * from "./nodes";
 export * from "./scopes";

src/nodes/typeGuards/single.ts

@@ -1187,3 +1187,24 @@
 export function isVoidKeyword(node: ts.Node): node is VoidKeyword {
  return node.kind === ts.SyntaxKind.VoidKeyword;
 }
+
+/**
+ * Test if a node has a `flowNode` property.
+ *
+ * @category Nodes - Type Guards
+ * @example
+ * ```ts
+ * declare const node: ts.Node;
+ *
+ * if (hasFlowNode(node)) {
+ * // ...
+ * }
+ * ```
+ *
+ * @returns Whether the given node has a `flowNode` property.
+ */
+export function hasFlowNode(
+ node: ts.Node
+): node is ts.Node & { flowNode: ts.FlowNode } {
+ return "flowNode" in node;
+}