From 48987e186a5eb33c652d7a5eddd987a8ee4670cd Mon Sep 17 00:00:00 2001
From: William Jackson <matabele.bill@gmail.com>
Date: Mon, 28 Dec 2015 10:31:39 +0200
Subject: [PATCH] Tidied up the code in the filters

---
 core/modules/filters/x-listops.js | 329 +++++++++++++++---------------
 1 file changed, 163 insertions(+), 166 deletions(-)

diff --git a/core/modules/filters/x-listops.js b/core/modules/filters/x-listops.js
index 63edcd142..a20fd5646 100644
--- a/core/modules/filters/x-listops.js
+++ b/core/modules/filters/x-listops.js
@@ -8,185 +8,182 @@ Extended filter operators to manipulate the current list.
 \*/
 (function () {
 
-  /*jslint node: true, browser: true */
-  /*global $tw: false */
-  "use strict";
+    /*jslint node: true, browser: true */
+    /*global $tw: false */
+    "use strict";
 
-  var prepare_results = function (source) {
+    /*
+    Fetch titles from the current list
+    */
+    var prepare_results = function (source) {
     var results = [];
-    source(function (tiddler, title) {
-      results.push(title);
-    });
-    return results;
-  };
+        source(function (tiddler, title) {
+            results.push(title);
+        });
+        return results;
+    };
 
-  /*
-  Moves a number of items from the tail of the current list before the item named in the operand
-  */
-  exports.putbefore = function (source, operator, options) {
-    var results = prepare_results(source),
-        index = results.indexOf(operator.operand),
-        count = parseInt(operator.suffix) || 1;
-    if (index === -1) {
-      return results.slice(0, -1);
-    }
-    return results.slice(0, index).concat(results.slice(-count)).concat(results.slice(index, -count));
-  };
+    /*
+    Moves a number of items from the tail of the current list before the item named in the operand
+    */
+    exports.putbefore = function (source, operator) {
+        var results = prepare_results(source),
+            index = results.indexOf(operator.operand),
+            count = parseInt(operator.suffix) || 1;
+        return (index === -1) ?
+            results.slice(0, -1) :
+            results.slice(0, index).concat(results.slice(-count)).concat(results.slice(index, -count));
+    };
 
-  /*
-  Moves a number of items from the tail of the current list after the item named in the operand
-  */
-  exports.putafter = function (source, operator, options) {
-    var results = prepare_results(source),
-        index = results.indexOf(operator.operand),
-        count = parseInt(operator.suffix) || 1;
-    if (index === -1) {
-      return results.slice(0, -1);
-    }
-    return results.slice(0, index + 1).concat(results.slice(-count)).concat(results.slice(index + 1, -count));
-  };
+    /*
+    Moves a number of items from the tail of the current list after the item named in the operand
+    */
+    exports.putafter = function (source, operator) {
+        var results = prepare_results(source),
+            index = results.indexOf(operator.operand),
+            count = parseInt(operator.suffix) || 1;
+        return (index === -1) ?
+            results.slice(0, -1) :
+            results.slice(0, index + 1).concat(results.slice(-count)).concat(results.slice(index + 1, -count));
+    };
 
-  /*
-  Replaces the item named in the operand with a number of items from the tail of the current list
-  */
-  exports.replace = function (source, operator, options) {
-    var results = prepare_results(source),
-        index = results.indexOf(operator.operand),
-        count = parseInt(operator.suffix) || 1;
-    if (index === -1) {
-      return results.slice(0, -count);
-    }
-    return results.slice(0, index).concat(results.slice(-count)).concat(results.slice(index + 1, -count));
-  };
+    /*
+    Replaces the item named in the operand with a number of items from the tail of the current list
+    */
+    exports.replace = function (source, operator) {
+        var results = prepare_results(source),
+            index = results.indexOf(operator.operand),
+            count = parseInt(operator.suffix) || 1;
+        return (index === -1) ?
+            results.slice(0, -count) :
+            results.slice(0, index).concat(results.slice(-count)).concat(results.slice(index + 1, -count));
+    };
 
-  /*
-  Moves a number of items from the tail of the current list to the head of the list
-  */
-  exports.putfirst = function (source, operator, options) {
-    var results = prepare_results(source),
-        count = parseInt(operator.suffix) || 1;
-    return results.slice(-count).concat(results.slice(0, -count));
-  };
+    /*
+    Moves a number of items from the tail of the current list to the head of the list
+    */
+    exports.putfirst = function (source, operator) {
+        var results = prepare_results(source),
+            count = parseInt(operator.suffix) || 1;
+        return results.slice(-count).concat(results.slice(0, -count));
+    };
 
-  /*
-  Moves a number of items from the head of the current list to the tail of the list
-  */
-  exports.putlast = function (source, operator, options) {
-    var results = prepare_results(source),
-        count = parseInt(operator.suffix) || 1;
-    return results.slice(count).concat(results.slice(0, count));
-  };
+    /*
+    Moves a number of items from the head of the current list to the tail of the list
+    */
+    exports.putlast = function (source, operator) {
+        var results = prepare_results(source),
+            count = parseInt(operator.suffix) || 1;
+        return results.slice(count).concat(results.slice(0, count));
+    };
 
-/*
-  Moves the item named in the operand a number of places forward or backward in the list
-  */
-  exports.move = function (source, operator, options) {
-    var results = prepare_results(source),
-        index = results.indexOf(operator.operand),
-        count = parseInt(operator.suffix) || 1,
-        marker = results.splice(index, 1);
-    return results.slice(0, index + count).concat(marker).concat(results.slice(index + count));
-  };
+    /*
+    Moves the item named in the operand a number of places forward or backward in the list
+    */
+    exports.move = function (source, operator) {
+        var results = prepare_results(source),
+            index = results.indexOf(operator.operand),
+            count = parseInt(operator.suffix) || 1,
+            marker = results.splice(index, 1);
+        return results.slice(0, index + count).concat(marker).concat(results.slice(index + count));
+    };
 
-  /*
-  Returns the items from the current list that are after the item named in the operand
-  */
-  exports.allafter = function (source, operator, options) {
-    var results = prepare_results(source),
-        index = results.indexOf(operator.operand);
-    if (index === -1 || index > (results.length - 2)) {
-      return [];
-    }
-    if (operator.suffix) {
-      return results.slice(index);
-    }
-    return results.slice(index + 1);
-  };
+    /*
+    Returns the items from the current list that are after the item named in the operand
+    */
+    exports.allafter = function (source, operator) {
+        var results = prepare_results(source),
+            index = results.indexOf(operator.operand);
+        return (index === -1 || index > (results.length - 2)) ? [] :
+            (operator.suffix) ? results.slice(index) :
+            results.slice(index + 1);
+    };
 
-  /*
-  Returns the items from the current list that are before the item named in the operand
-  */
-  exports.allbefore = function (source, operator, options) {
-    var results = prepare_results(source),
-        index = results.indexOf(operator.operand);
-    if (index <= 0) {
-      return [];
-    } 
-    if (operator.suffix) {
-      return results.slice(0, index + 1);
-    }
-    return results.slice(0, index);
-  };
+    /*
+    Returns the items from the current list that are before the item named in the operand
+    */
+    exports.allbefore = function (source, operator) {
+        var results = prepare_results(source),
+            index = results.indexOf(operator.operand);
+        return (index <= 0) ? [] :
+            (operator.suffix) ? results.slice(0, index + 1) :
+            results.slice(0, index);
+    };
 
-  /*
-  Appends the items listed in the operand array to the tail of the current list 
-  */
-  exports.append = function (source, operator, options) {
-    var append = $tw.utils.parseStringArray(operator.operand),
-        results = prepare_results(source),
-        count = parseInt(operator.suffix) || append.length;
-    if (append.length === 0) {
-      return results;
-    }
-    if (operator.prefix) {
-        return results.concat(append.slice(-count));
-    } else {
-        return results.concat(append.slice(0, count));
-    }
-  };
+    /*
+    Appends the items listed in the operand array to the tail of the current list
+    */
+    exports.append = function (source, operator) {
+        var append = $tw.utils.parseStringArray(operator.operand, "true"),
+            results = prepare_results(source),
+            count = parseInt(operator.suffix) || append.length;
+        return (append.length === 0) ? results :
+            (operator.prefix) ? results.concat(append.slice(-count)) :
+            results.concat(append.slice(0, count));
+    };
 
-  /*
-  Prepends the items listed in the operand array to the head of the current list 
-  */
-  exports.prepend = function (source, operator, options) {
-      var prepend = $tw.utils.parseStringArray(operator.operand),
-          results = prepare_results(source),
-          count = parseInt(operator.suffix) || prepend.length;  
-    if (prepend.length === 0) {
-      return results;
-    }
-    if (operator.prefix) {
-        return prepend.slice(-count).concat(results);
-    } else {
-        return prepend.slice(0, count).concat(results);
-    }
-  };
+    /*
+    Prepends the items listed in the operand array to the head of the current list
+    */
+    exports.prepend = function (source, operator) {
+        var prepend = $tw.utils.parseStringArray(operator.operand, "true"),
+            results = prepare_results(source),
+            count = parseInt(operator.suffix) || prepend.length;
+        return (prepend.length === 0) ? results :
+            (operator.prefix) ? prepend.slice(-count).concat(results) :
+            prepend.slice(0, count).concat(results);
+    };
 
-  /*
-  Returns all items from the current list except the items listed in the operand array
-  */
-  exports.remove = function (source, operator, options) {
-    var array = $tw.utils.parseStringArray(operator.operand),
-        results = prepare_results(source),
-        count = parseInt(operator.suffix) || array.length,
-        p, len, index;
-    len = array.length - 1;
-    for (p = 0; p < count; ++p) {
-      if (operator.prefix) {
-        index = results.indexOf(array[len - p]);
-      } else {
-        index = results.indexOf(array[p]);
-      }
-      if (index !== -1) {
-        results.splice(index, 1);
-      }
-    }
-    return results;
-  };
+    /*
+    Returns all items from the current list except the items listed in the operand array
+    */
+    exports.remove = function (source, operator) {
+        var array = $tw.utils.parseStringArray(operator.operand, "true"),
+            results = prepare_results(source),
+            count = parseInt(operator.suffix) || array.length,
+            p,
+            len,
+            index;
+        len = array.length - 1;
+        for (p = 0; p < count; ++p) {
+            if (operator.prefix) {
+                index = results.indexOf(array[len - p]);
+            } else {
+                index = results.indexOf(array[p]);
+            }
+            if (index !== -1) {
+                results.splice(index, 1);
+            }
+        }
+        return results;
+    };
 
-  /*
-  Returns all items from the current list sorted in the order of the items in the operand array
-  */
-  exports.sortby = function (source, operator, options) {
-    var results = prepare_results(source);
-    if (!results || results.length < 2) {
-      return results;
-    }
-    var lookup = $tw.utils.parseStringArray(operator.operand);
-    results.sort(function (a, b) {
-      return lookup.indexOf(a) - lookup.indexOf(b);
-    });
-    return results;
-  };
+    /*
+    Returns all items from the current list sorted in the order of the items in the operand array
+    */
+    exports.sortby = function (source, operator) {
+        var results = prepare_results(source);
+        if (!results || results.length < 2) {
+            return results;
+        }
+        var lookup = $tw.utils.parseStringArray(operator.operand, "true");
+        results.sort(function (a, b) {
+            return lookup.indexOf(a) - lookup.indexOf(b);
+        });
+        return results;
+    };
 
+    /*
+    Removes all duplicate items from the current list
+    */
+    exports.unique = function (source, operator) {
+        var results = prepare_results(source);
+        var set = results.reduce(function (a, b) {
+            if (a.indexOf(b) < 0) {
+                a.push(b);
+            }
+            return a;
+        }, []);
+        return set;
+    };
 })();