Add implementation-sniffing to .stream()

balderdashy · May 29, 2018 · 7fd0fed · 7fd0fed
1 parent dce4c0f
commit 7fd0fed
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Showing 2 changed files with 40 additions and 11 deletions.
diff --git a/.eslintrc b/.eslintrc
@@ -58,7 +58,7 @@
     "no-trailing-spaces":           ["warn"],
     "no-undef":                     ["error"],
     "no-unexpected-multiline":      ["warn"],
-    "no-unused-vars":               ["warn", {"caughtErrors":"all", "caughtErrorsIgnorePattern": "^unused($|[A-Z].*$)"}],
+    "no-unused-vars":               ["warn", {"caughtErrors":"all", "caughtErrorsIgnorePattern": "^unused($|[A-Z].*$)", "argsIgnorePattern": "^unused($|[A-Z].*$)", "varsIgnorePattern": "^unused($|[A-Z].*$)" }],
     "no-use-before-define":         ["error", {"functions":false}],
     "one-var":                      ["warn", "never"],
     "quotes":                       ["warn", "single", {"avoidEscape":false, "allowTemplateLiterals":true}],

diff --git a/lib/waterline/methods/stream.js b/lib/waterline/methods/stream.js
@@ -10,12 +10,12 @@ var forgeStageTwoQuery = require('../utils/query/forge-stage-two-query');
 var getQueryModifierMethods = require('../utils/query/get-query-modifier-methods');
 var verifyModelMethodContext = require('../utils/query/verify-model-method-context');
 
-
 /**
  * Module constants
  */
 
 var DEFERRED_METHODS = getQueryModifierMethods('stream');
+var STRIP_COMMENTS_RX = /(\/\/.*$)|(\/\*[\s\S]*?\*\/)|(\s*=[^,\)]*(('(?:\\'|[^'\r\n])*')|("(?:\\"|[^"\r\n])*"))|(\s*=[^,\)]*))/mg;
 
 
 
@@ -341,6 +341,15 @@ module.exports = function stream( /* criteria?, eachRecordFn?, explicitCbMaybe?,
           // once.  If it's eachRecordFn, we'll call it once per record.
           (function _makeCallOrCallsToAppropriateIteratee(proceed){
 
+            // Check if the iteratee declares a callback parameter
+            var seemsToExpectCallback = (function(){
+              var fn = query.eachBatchFn || query.eachRecordFn;
+              var fnStr = fn.toString().replace(STRIP_COMMENTS_RX, '');
+              var parametersAsString = fnStr.slice(fnStr.indexOf('(')+1, fnStr.indexOf(')'));
+              // console.log(':seemsToExpectCallback:',parametersAsString, !!parametersAsString.match(/\,\s*([^,\{\}\[\]\s]+)\s*$/));
+              return !! parametersAsString.match(/\,\s*([^,\{\}\[\]\s]+)\s*$/);
+            })();//†
+
             // If an `eachBatchFn` iteratee was provided, we'll call it.
             // > At this point we already know it's a function, because
             // > we validated usage at the very beginning.
@@ -351,10 +360,9 @@ module.exports = function stream( /* criteria?, eachRecordFn?, explicitCbMaybe?,
               // that occur after the first.
               var didIterateeAlreadyHalt;
               try {
-                // TODO: handle stream iteratees with no declared callback parameter
                 var promiseMaybe = query.eachBatchFn(batchOfRecords, function (err) {
-                  if (err) { return proceed(err); }
-
+                  if (!seemsToExpectCallback) { return proceed(new Error('Unexpected attempt to invoke callback.  Since this per-batch iteratee function does not appear to expect a callback parameter, this stub callback was provided instead.  Please either explicitly list the callback parameter among the arguments or change this code to no longer use a callback.')); }//•
+                  if (err) { return proceed(err); }//•
                   if (didIterateeAlreadyHalt) {
                     console.warn(
                       'Warning: The per-batch iteratee provided to `.stream()` triggered its callback \n'+
@@ -363,15 +371,24 @@ module.exports = function stream( /* criteria?, eachRecordFn?, explicitCbMaybe?,
                     );
                     return;
                   }//-•
-
                   didIterateeAlreadyHalt = true;
-
                   return proceed();
                 });//_∏_  </ invoked per-batch iteratee >
 
-                // Take care of unhandled promise rejections from `await`.
+                // Take care of unhandled promise rejections from `await` (if appropriate)
                 if (query.eachBatchFn.constructor.name === 'AsyncFunction') {
+                  if (!seemsToExpectCallback) {
+                    promiseMaybe = promiseMaybe.then(function(){
+                      didIterateeAlreadyHalt = true;
+                      proceed();
+                    });//_∏_
+                  }//ﬁ
                   promiseMaybe.catch(function(e){ proceed(e); });//_∏_
+                } else {
+                  if (!seemsToExpectCallback) {
+                    didIterateeAlreadyHalt = true;
+                    return proceed();
+                  }
                 }
 
               } catch (e) { return proceed(e); }//>-•
@@ -391,8 +408,8 @@ module.exports = function stream( /* criteria?, eachRecordFn?, explicitCbMaybe?,
               // that occur after the first.
               var didIterateeAlreadyHalt;
               try {
-                // TODO: handle stream iteratees with no declared callback parameter
                 var promiseMaybe = query.eachRecordFn(record, function (err) {
+                  if (!seemsToExpectCallback) { return next(new Error('Unexpected attempt to invoke callback.  Since this per-record iteratee function does not appear to expect a callback parameter, this stub callback was provided instead.  Please either explicitly list the callback parameter among the arguments or change this code to no longer use a callback.')); }//•
                   if (err) { return next(err); }
 
                   if (didIterateeAlreadyHalt) {
@@ -410,10 +427,22 @@ module.exports = function stream( /* criteria?, eachRecordFn?, explicitCbMaybe?,
 
                 });//_∏_  </ invoked per-record iteratee >
 
-                // Take care of unhandled promise rejections from `await`.
+                // Take care of unhandled promise rejections from `await` (if appropriate)
                 if (query.eachRecordFn.constructor.name === 'AsyncFunction') {
+                  if (!seemsToExpectCallback) {
+                    promiseMaybe = promiseMaybe.then(function(){
+                      didIterateeAlreadyHalt = true;
+                      next();
+                    });//_∏_
+                  }//ﬁ
                   promiseMaybe.catch(function(e){ next(e); });//_∏_
-                }
+                } else {
+                  if (!seemsToExpectCallback) {
+                    didIterateeAlreadyHalt = true;
+                    return next();
+                  }
+                }//ﬂ
+
               } catch (e) { return next(e); }
 
             },// ~∞%°