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import {
ASTNode,
StackFrame,
Evaluate,
EmptyStackFrame,
NodeType,
FnPrim,
SENTINEL_NO_BUILTIN,
} from "../../ts-lang";
import { nameToBUILTIN, nameToSBUILTIN } from "../builtin";
const V_SENTINEL_NO_BUILTIN: SENTINEL_NO_BUILTIN = "__NO_BUILTIN__";
const mapBuiltins = (node: ASTNode, frame: StackFrame): any => {
if (node.name in nameToSBUILTIN) {
return nameToSBUILTIN[node.name](node, frame);
}
if (node.name in nameToBUILTIN) {
return nameToBUILTIN[node.name](getEvaluatedChildren(node, frame));
}
return V_SENTINEL_NO_BUILTIN;
};
const findInStack = (frame: StackFrame, nameToFind: string) => {
if (nameToFind in frame.bindings) {
return frame.bindings[nameToFind];
}
throw new Error(`Can't find name ${nameToFind} on the stack`);
};
const handleBind = (node: ASTNode, frame: StackFrame) => {
const inner = _evaluate(node.children[1], frame);
if (inner.fn) {
return [inner, frame, node.children[0]["name"]];
}
return inner;
};
const handleFn = (node: ASTNode): FnPrim => {
const fn = node.children[node.children.length - 1];
return {
args: node.children.slice(0, node.children.length - 1),
fn,
};
};
const mapZip = (args: ASTNode[], values: any[]) =>
Object.fromEntries(args.map(({ name }, i) => [name, values[i]]));
export const callFn = (
fn: FnPrim | [FnPrim, StackFrame, ASTNode["name"]],
values: any[],
frame: StackFrame
) => {
if (Array.isArray(fn)) {
const [prim, frame, name] = fn;
return _evaluate(prim.fn, {
bindings: {
...frame.bindings,
[name]: fn,
...mapZip(prim.args as ASTNode[], values),
},
});
}
return _evaluate(fn.fn, {
bindings: { ...frame.bindings, ...mapZip(fn.args as ASTNode[], values) },
});
};
export const _evaluate = (node: ASTNode, frame: StackFrame): any => {
if (node.type === NodeType.INT) {
return node.value;
}
if (node.type === NodeType.EXT) {
if (node.name === "fn") {
return handleFn(node);
}
if (node.name === "bind") {
return handleBind(node, frame);
}
const builtinResult = mapBuiltins(node, frame);
if (builtinResult !== V_SENTINEL_NO_BUILTIN) {
return builtinResult;
}
return findInStack(frame, node.name);
}
throw new Error(`Unhandled node type ${node.type}`);
};
export const getEvaluatedChildren = (node: ASTNode, frame: StackFrame) =>
node.children.map((child) => _evaluate(child, frame));
export const emptyStackFrame: EmptyStackFrame = { bindings: {} };
export const evaluate = <const Node extends ASTNode>(
node: Node
): Evaluate<Node> => _evaluate(node, emptyStackFrame) as Evaluate<Node>;
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