systemjs-builder/lib/arithmetic.js

var asp = require('bluebird').promisify;
var Promise = require('bluebird');
var glob = require('glob');
var path = require('path');
var url = require('url');

var getLoadDependencies = require('./trace').getLoadDependencies;

var fromFileURL = require('./utils').fromFileURL;
var toFileURL = require('./utils').toFileURL;

var verifyTree = require('./utils').verifyTree;

function parseExpression(expressionString) {
  expressionString = ' + ' + expressionString;

  var index = 0;
  var operations = [];
  var operatorRegex = /[\+\-\&]/;
  var errorMessagesFromIndex = 3;

  function getNextIdentifier() {
    eatWhitespace();
    var firstChar = expressionString.charAt(index);

    if (operatorRegex.test(firstChar)){
      throw 'Syntax Error: Identifier or sub expression expected after <' + expressionString.slice(errorMessagesFromIndex).substr(0, index - errorMessagesFromIndex) + '> but found <' + firstChar + '> instead';
    }

    if (firstChar === '(') {
      var closingParenIndex = index,
          numOpenBeforeSelf = 0;

      while (++closingParenIndex < expressionString.length){
        if (expressionString.charAt(closingParenIndex) === '('){
          numOpenBeforeSelf++;
        } else if (expressionString.charAt(closingParenIndex) === ')') {
          if (numOpenBeforeSelf){
            numOpenBeforeSelf--;
          } else {
            break;
          }
        }
      }
      if (expressionString.charAt(closingParenIndex) !== ')'){
        throw 'Syntax Error: Expression <' + expressionString.substr(index) + '> is never terminated. Did you forget to add a closing ")"?';
      }

      var wholeExpression = expressionString.substring(index + 1, closingParenIndex);
      index = closingParenIndex + 1;
      return { bulkOperation: wholeExpression };
    }

    var result = "";
    //scan the identifier
    for (; index < expressionString.length; index++) {
      var currentChar = expressionString.charAt(index);
      //can have spaces in file names - so we need whitespace, operator, whitespace.
      if (/^\s+[\+\-\&]\s+/.test(expressionString.substr(index))) {
        return result;
      } else {
        result += currentChar;
      }
    }
    return result.replace(/\s+$/, ''); //it appears as though trailing whitespace is trimmed downstream, but I'm snipping here to be safe
  }

  function getNextOperator() {
    eatWhitespace();
    if (index === expressionString.length) return null;

    var candidateResult = expressionString.charAt(index++); //all operators are single characters at the moment

    if (!operatorRegex.test(candidateResult)){
      throw 'Syntax Error: An operator was expected after <' + expressionString.slice(errorMessagesFromIndex).substr(0, index - 1 - errorMessagesFromIndex) + '> but found <' + expressionString.substring(index - 1) + '> instead';
    }

    return candidateResult;
  }

  function eatWhitespace() {
    //wind past whitespace
    for (; index < expressionString.length; index++) {
      if (/\S/.test(expressionString.charAt(index))) {
        break;
      }
    }
  }

  var operator;
  while (index < expressionString.length && (operator = getNextOperator())) {
    var moduleNameOrSubExpression = getNextIdentifier();

    if (typeof moduleNameOrSubExpression === 'object'){
      operations.push({
        operator: operator,
        bulkOperation: moduleNameOrSubExpression.bulkOperation
      });
    } else {
      // detect [moduleName] syntax for individual modules not trees
      var singleModule = moduleNameOrSubExpression.substr(0, 1) == '[' && moduleNameOrSubExpression.substr(moduleNameOrSubExpression.length - 1, 1) == ']';
      if (singleModule) {
        moduleNameOrSubExpression = moduleNameOrSubExpression.substr(1, moduleNameOrSubExpression.length - 2);
      }

      var canonicalized = moduleNameOrSubExpression.substr(0, 1) == '`' && moduleNameOrSubExpression.substr(moduleNameOrSubExpression.length - 1, 1) == '`';
      if (canonicalized) {
        moduleNameOrSubExpression = moduleNameOrSubExpression.substr(1, moduleNameOrSubExpression.length - 2);
      }

      operations.push({
        operator: operator,
        moduleName: moduleNameOrSubExpression,
        singleModule: singleModule,
        canonicalized: canonicalized
      });
    }
  }

  return operations;
}

function getTreeOperation(symbol) {
  if (symbol == '+')
    return addTrees;
  else if (symbol == '-')
    return subtractTrees;
  else if (symbol == '&')
    return intersectTrees;
  else
    throw new TypeError('Unknown operator ' + symbol);
}

function getTreeModuleOperation(builder, symbol, traceOpts) {
  if (symbol == '+')
    return function(tree, canonical) {
      var addedTree = {};
      for (var p in tree)
        addedTree[p] = tree[p];

      return builder.tracer.getLoadRecord(canonical, traceOpts).then(function(load) {
        addedTree[canonical] = load;
        return addedTree;
      });
    };
  else if (symbol == '-')
    return function(tree, canonical) {
      var subtractedTree = {};
      for (var p in tree) {
        if (p != canonical)
          subtractedTree[p] = tree[p];
      }
      return subtractedTree;
    };
  else if (symbol == '&')
    throw new TypeError('Single modules cannot be intersected.');
  else
    throw new TypeError('Unknown operator ' + symbol);
}

function expandGlobAndCanonicalize(builder, operation) {
  var loader = builder.loader;

  // no glob -> just canonicalize
  if (operation.moduleName.indexOf('*') == -1) {
    if (operation.canonicalized)
      return [operation];

    return loader.normalize(operation.moduleName)
    .then(function(normalized) {
      operation.moduleName = builder.getCanonicalName(normalized);
      return [operation];
    });
  }

  // globbing
  var metadata = {};
  var globSuffix = operation.moduleName[operation.moduleName.length - 1] == '*';
  var pluginSyntax = operation.moduleName.indexOf('!') != -1;

  return Promise.resolve()
  .then(function() {
    if (operation.canonicalized) {
      return loader.decanonicalize(operation.moduleName);
    }
    else {
      // normalizeSync avoids package config loading which we don't want for wildcards
      return loader.normalizeSync(operation.moduleName);
    }
  })
  .then(function(normalized) {
    // remove ALL extension adding when globbing
    if (globSuffix && !operation.canonicalized) {
      var extIndex = normalized.lastIndexOf('.');
      if (extIndex != -1 && normalized[extIndex - 1] == '*')
        normalized = normalized.substr(0, extIndex);
    }

    return loader.locate({ name: normalized, metadata: metadata });
  })
  .then(function(address) {
    // now we have a file path to glob -> glob the pattern
    return asp(glob)(fromFileURL(address), {
      nobrace: true,
      noext: true,
      nodir: true
    });
  })
  .then(function(addresses) {
    return (metadata.loader && pluginSyntax ? loader.normalize(metadata.loader) : Promise.resolve())
    .then(function(loaderSyntaxName) {
      return addresses.map(function(file) {
        return {
          operator: operation.operator,
          moduleName: builder.getCanonicalName(toFileURL(file) + (loaderSyntaxName ? '!' + loader.getCanonicalName(loaderSyntaxName) : '')),
          singleModule: operation.singleModule
        };
      });
    });
  });
}

exports.traceExpression = function(builder, expression, traceOpts) {
  if (!expression)
    throw new Error('A module expression must be provided to trace.');

  if (expression instanceof Array) {
    var tree = {};
    return Promise.all(expression.map(function(moduleName) {
      return builder.loader.normalize(moduleName)
      .then(function(normalized) {
        var canonical = builder.getCanonicalName(normalized);
        return builder.tracer.getLoadRecord(canonical, traceOpts)
        .then(function(load) {
          tree[canonical] = load;
        });
      });
    }))
    .then(function() {
      return tree;
    });
  }

  return Promise
    .resolve(expandAndCanonicalizeExpression(builder, expression))
    .then(function processExpandedOperations(expandedOperations) {
      // chain the operations, applying them with the trace of the next module
      return expandedOperations.reduce(function(p, op) {
        return p.then(function(curTree) {
          // tree . module
          if (op.singleModule)
            return getTreeModuleOperation(builder, op.operator, traceOpts)(curTree, op.moduleName);

          if (op.operationsTree){
            return processExpandedOperations(op.operationsTree).then(function(expandedTree){
              return getTreeOperation(op.operator)(curTree, expandedTree);
            });
          }
          // tree . tree
          return builder.tracer.traceCanonical(op.moduleName, traceOpts)
          .then(function(nextTrace) {
            return getTreeOperation(op.operator)(curTree, nextTrace.tree);
          });
        });
      }, Promise.resolve({}));
  });
};

function expandAndCanonicalizeExpression(builder, expression) {
  var operations = parseExpression(expression);
  var expandPromise = Promise.resolve(1);
  var expandedOperations = [];

  operations.forEach(function(operation){
    if (operation.bulkOperation) {
      var expandedTreePromise = expandAndCanonicalizeExpression(builder, operation.bulkOperation);
      expandPromise = expandPromise.then(function() {
        return Promise.resolve(expandedTreePromise)
              .then(function(expressionsOperations){
                expandedOperations = expandedOperations.concat({ operator: operation.operator, operationsTree: expressionsOperations });
              });
      });
    } else {
      expandPromise = expandPromise.then(function() {
        return Promise.resolve(expandGlobAndCanonicalize(builder, operation))
               .then(function (expanded) {
                 expandedOperations = expandedOperations.concat(expanded);
               });
      })
    }
  });

  return Promise.resolve(expandPromise).then(function(){ return expandedOperations; });
}

// returns a new tree containing tree1 n tree2
exports.intersectTrees = intersectTrees;
function intersectTrees(tree1, tree2) {
  verifyTree(tree1);
  verifyTree(tree2);

  var name;
  var intersectTree = {};

  var tree1Names = [];
  for (name in tree1)
    tree1Names.push(name);

  for (name in tree2) {
    if (tree1Names.indexOf(name) == -1)
      continue;
    // intersect deps layer (load: false) and actual bundle includes separately
    if (tree1[name] === false && tree2[name] === false)
      continue;

    intersectTree[name] = tree1[name] || tree2[name];
  }

  return intersectTree;
}

// returns a new tree containing tree1 + tree2
exports.addTrees = addTrees;
function addTrees(tree1, tree2) {
  verifyTree(tree1);
  verifyTree(tree2);

  var name;
  var unionTree = {};

  for (name in tree2)
    unionTree[name] = tree2[name];

  for (name in tree1)
    if (!(name in unionTree))
      unionTree[name] = tree1[name];

  return unionTree;
}

// returns a new tree containing tree1 - tree2
exports.subtractTrees = subtractTrees;
function subtractTrees(tree1, tree2) {
  verifyTree(tree1);
  verifyTree(tree2);

  var name;
  var subtractTree = {};

  for (name in tree1)
    subtractTree[name] = tree1[name];

  for (name in tree2) {
    if (tree2[name] !== false)
      delete subtractTree[name];
  }

  return subtractTree;
}

// pre-order tree traversal with a visitor and stop condition
exports.traverseTree = traverseTree;
function traverseTree(tree, moduleName, visitor, traceOpts, reversePost, parent, seen) {
  if (!seen) {
    // NB traceOpts.conditions should be strictly canonicalized on the first run
    traceOpts = traceOpts || {};
    verifyTree(tree);
  }

  seen = seen || [];
  seen.push(moduleName);
  parent = parent || null;

  var curNode = tree[moduleName];

  if (curNode && visitor(moduleName, parent) !== false) {
    var deps = getLoadDependencies(curNode, traceOpts, traceOpts.conditions, traceOpts.inlineConditions);
    if (reversePost)
      deps = deps.reverse();
    deps.forEach(function(dep) {
      if (seen.indexOf(dep) == -1)
        traverseTree(tree, dep, visitor, traceOpts, reversePost, moduleName, seen);
    });
  }
}