simple-router.js

/**
 * @license
 * MIT License
 *
 * Copyright (c) 2020 Alexis Munsayac
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 *
 * @author Alexis Munsayac <alexis.munsayac@gmail.com>
 * @copyright Alexis Munsayac 2020
 */
class SharedKeyError extends Error {
  constructor() {
    super('Shared key detected');
  }
}
class DuplicateKeyError extends Error {
  constructor() {
    super('Duplicate key detected');
  }
}
function createRouterNode(key, value) {
  return {
    key,
    value,
    normal: [],
  };
}

function addToChildren(
  children,
  key,
  value,
) {
  const node = createRouterNode(key, value);
  children.push(node);
  return node;
}

function addRoute(
  parent,
  [lead, ...names],
  value,
) {
  function addRouteToChildren(children) {
    for (let i = 0; i < children.length; i += 1) {
      const child = children[i];

      if (child.key === lead) {
        if (names.length > 0) {
          addRoute(child, names, value);
          return;
        }
        throw new DuplicateRouterPathError(child.key);
      }
    }

    const node = addToChildren(children, lead);

    if (names.length > 0) {
      addRoute(node, names, value);
    } else {
      node.key = lead;
      node.value = value;
    }
  }

  if (lead.startsWith('[')) {
    if (lead.endsWith(']')) {
      if (lead.startsWith('[...')) {
        if (parent.glob) {
          throw new SharedRouterPathError(
            lead,
            parent.glob.key,
          );
        }
        parent.glob = createRouterNode(lead, value);
        return;
      }
      if (parent.named) {
        if (lead !== parent.named.key) {
          throw new SharedRouterPathError(
            lead,
            parent.named.key,
          );
        }
      } else {
        parent.named = createRouterNode(lead);
        if (names.length > 0) {
          addRoute(parent.named, names, value);
        } else {
          parent.named.value = value;
        }
      }
      return;
    }
    throw new InvalidRouterSyntaxError(lead);
  }
  addRouteToChildren(parent.normal);
}

function matchRoute(
  parent,
  [lead, ...names],
  params = {},
) {
  // Find first if the lead exists in the normal children
  for (let i = 0; i < parent.normal.length; i += 1) {
    const child = parent.normal[i];

    if (child.key === lead) {
      if (names.length > 0) {
        const matched = matchRoute(child, names, {
          ...params,
        });

        if (matched) {
          return matched;
        }
      } else {
        return {
          value: child.value,
          params: {
            ...params,
          },
        };
      }
    }
  }

  // Check if the parent has a named parameter
  if (parent.named) {
    if (names.length > 0) {
      const namedKey = parent.named.key;
      const paramKey = namedKey.substring(1, namedKey.length - 1);
      const matched = matchRoute(parent.named, names, {
        ...params,
        [paramKey]: lead,
      });

      if (matched) {
        return matched;
      }
    } else {
      const namedKey = parent.named.key;
      const paramKey = namedKey.substring(1, namedKey.length - 1);
      return {
        value: parent.named.value,
        params: {
          ...params,
          [paramKey]: lead,
        },
      };
    }
  }

  if (parent.glob) {
    const globKey = parent.glob.key;
    const paramKey = globKey.substring(4, globKey.length - 1);
    return {
      value: parent.glob.value,
      params: {
        ...params,
        [paramKey]: [lead, ...names],
      },
    };
  }
  return undefined;
}

const tree = createRouterNode('');
addRoute(tree, ['a'], 'normal');
addRoute(tree, ['[b]'], 'params');
addRoute(tree, ['[...all]'], 'glob');

console.dir(tree, {
  depth: null,
});
console.log(matchRoute(tree, ['a', 'b']));