react-docgen/dist/utils/findFunctionReturn.js

A library to extract information from React components for documentation generation.

import { visitors } from '@babel/traverse';
import resolveToValue from './resolveToValue.js';
import { ignore } from './traverse.js';
const explodedVisitors = visitors.explode({
    Function: { enter: ignore },
    Class: { enter: ignore },
    ObjectExpression: { enter: ignore },
    ReturnStatement: {
        enter: function (path, state) {
            const argument = path.get('argument');
            if (argument.hasNode()) {
                const resolvedPath = resolvesToFinalValue(argument, state.predicate, state.seen);
                if (resolvedPath) {
                    state.resolvedReturnPath = resolvedPath;
                    path.stop();
                }
            }
        },
    },
});
function resolvesToFinalValue(path, predicate, seen) {
    // avoid returns with recursive function calls
    if (seen.has(path)) {
        return;
    }
    seen.add(path);
    // Is the path already passes then return it.
    if (predicate(path)) {
        return path;
    }
    const resolvedPath = resolveToValue(path);
    // If the resolved path is already passing then no need to further check
    // Only do this if the resolvedPath actually resolved something as otherwise we did this check already
    if (resolvedPath.node !== path.node && predicate(resolvedPath)) {
        return resolvedPath;
    }
    // If the path points to a conditional expression, then we need to look only at
    // the two possible paths
    if (resolvedPath.isConditionalExpression()) {
        return (resolvesToFinalValue(resolvedPath.get('consequent'), predicate, seen) ||
            resolvesToFinalValue(resolvedPath.get('alternate'), predicate, seen));
    }
    // If the path points to a logical expression (AND, OR, ...), then we need to look only at
    // the two possible paths
    if (resolvedPath.isLogicalExpression()) {
        return (resolvesToFinalValue(resolvedPath.get('left'), predicate, seen) ||
            resolvesToFinalValue(resolvedPath.get('right'), predicate, seen));
    }
    // If we have a call expression, lets try to follow it
    if (resolvedPath.isCallExpression()) {
        const returnValue = findFunctionReturnWithCache(resolveToValue(resolvedPath.get('callee')), predicate, seen);
        if (returnValue) {
            return returnValue;
        }
    }
    return;
}
/**
 * This can be used in two ways
 * 1. Find the first return path that passes the predicate function
 *    (for example to check if a function is returning something)
 * 2. Find all occurrences of return values
 *    For this the predicate acts more like a collector and always needs to return false
 */
function findFunctionReturnWithCache(path, predicate, seen) {
    let functionPath = path;
    if (functionPath.isObjectProperty()) {
        functionPath = functionPath.get('value');
    }
    else if (functionPath.isClassProperty()) {
        const classPropertyValue = functionPath.get('value');
        if (classPropertyValue.hasNode()) {
            functionPath = classPropertyValue;
        }
    }
    if (!functionPath.isFunction()) {
        return;
    }
    // skip traversing for ArrowFunctionExpressions with no block
    if (path.isArrowFunctionExpression()) {
        const body = path.get('body');
        if (!body.isBlockStatement()) {
            return resolvesToFinalValue(body, predicate, seen);
        }
    }
    const state = {
        predicate,
        seen,
    };
    path.traverse(explodedVisitors, state);
    return state.resolvedReturnPath;
}
/**
 * This can be used in two ways
 * 1. Find the first return path that passes the predicate function
 *    (for example to check if a function is returning something)
 * 2. Find all occurrences of return values
 *    For this the predicate acts more like a collector and always needs to return false
 */
export default function findFunctionReturn(path, predicate) {
    return findFunctionReturnWithCache(path, predicate, new WeakSet());
}