Adds count viewport setting

doc/taskwiki.txt

@@ -387,8 +387,28 @@ viewport definition:
 
 ~   == Differently ordered home tasks | project:Home $T ==
 
+------------------
+5.2.4 Limiting number of tasks displayed
+
+By default, taskwiki will present the full list of tasks that match the
+viewport definition.
+
+You can limit the number of tasks listed by using the limit filter:
+
+~   == List only the 5 first tasks | project:Home limit:5 ==
+
+This will instruct taskwiki to limit the list of tasks to 5.
+
+The limit must always come last. For instance, if you are also using a sorting
+identifier:
+
+~   == List only the 5 first tasks | project:Home $T limit:5 ==
+
+The limit keyword will not be passed over to taskwarrior and is consumed only
+only by taskwiki.
+
 --------------------
-5.2.4 Default filter
+5.2.5 Default filter
 
 By default, every viewport filter is extended with the -DELETED and -PARENT
 virtual tags.
@@ -408,7 +428,7 @@ Examples:
 ~   == Home tasks, excluding deleted | project:Home !-DELETED ==
 
 -----------------------
-5.2.5 Meta virtual tags
+5.2.6 Meta virtual tags
 
 Currently there is one meta virtual tag: -VISIBLE. This tag can be used to
 filter out tasks that are displayed elsewhere in the same taskwiki file.
@@ -420,14 +440,14 @@ Example:
 ~    == Work review tasks | project:Work.Review ==
 
 ----------------
-5.2.6 Inspection
+5.2.7 Inspection
 
 You can inspect a given viewport (see what filter and defaults are being used,
 as well as other pieces of information) by using the |:TaskWikiInspect|
 command (or hitting <CR>) over a viewport definition.
 
 -------------------------------------------
-5.2.7 Usage of existing context definitions
+5.2.8 Usage of existing context definitions
 
 If you use the context feature in Taskwarrior, you can easily reference
 definition of any context using the @[context_name] syntax in the viewport's

taskwiki/regexp.py

@@ -60,6 +60,8 @@ VIEWPORT = {
         r'\s*'                           # Any whitespace
         r'(\$(?P<sort>[A-Z]))?'          # Optional sort indicator
         r'\s*'                           # Any whitespace
+        r'(limit:(?P<count>[0-9]+))?'    # Optional count indicator
+        r'\s*'                           # Any whitespace
         r'[=]+'                          # Header ending
     ),
     'markdown':
@@ -80,6 +82,8 @@ VIEWPORT = {
         r'\s*'                           # Any whitespace
         r'(\$(?P<sort>[A-Z]))?'          # Optional sort indicator
         r'\s*'                           # Any whitespace
+        r'(limit:(?P<count>[0-9]+))?'    # Optional count indicator
+        r'\s*'                           # Any whitespace
         r'$'                             # End of line
     )
 }

taskwiki/viewport.py

@@ -31,8 +31,17 @@ class ViewPort(object):
 
     meta_tokens = ('-VISIBLE',)
 
-    def __init__(self, line_number, cache, tw,
+    def __init__(
-                 name, filterstring, defaultstring, sort=None):
+        self,
+        line_number,
+        cache,
+        tw,
+        name,
+        filterstring,
+        defaultstring,
+        sort=None,
+        count=-1,
+    ):
         """
         Constructs a ViewPort out of given line.
         """
@@ -58,6 +67,8 @@ class ViewPort(object):
             constants.DEFAULT_SORT_ORDER
         )
 
+        self.count = count and int(count) or None
+
     def process_filterstring(self, filterstring, use_presets=True):
         """
         This method processes taskfilter in the form or filter string,
@@ -234,8 +245,10 @@ class ViewPort(object):
                 print(u"Sort indicator '{0}' for viewport '{1}' is not defined,"
                        " using default.".format(sort_id, name), sys.stderr)
 
+        count = match.group('count')
+
         self = cls(number, cache, tw, name, filterstring,
-                   defaults, sortstring)
+                   defaults, sortstring, count)
 
         return self
 
@@ -379,3 +392,10 @@ class ViewPort(object):
             self.cache.vwtask[added_at] = vimwikitask
 
         sort.TaskSorter(self.cache, self.tasks, self.sort).execute()
+
+        if self.count is not None:
+            for i in range(
+                self.line_number + self.count,
+                self.line_number + existing_tasks + added_tasks,
+            ):
+                self.cache.remove_line(self.line_number + self.count + 1)

tests/test_viewport.py

@@ -545,6 +545,30 @@ class TestViewportsSortedInvalidOrder(MultiSyntaxIntegrationTest):
             "'Work tasks' is not defined, using default.", lines=2)
 
 
+class TestViewportsCount(MultiSyntaxIntegrationTest):
+
+    viminput = """
+    HEADER2(Work tasks | project:Work or project:Home limit:2)
+    """
+
+    vimoutput = """
+    HEADER2(Work tasks | project:Work or project:Home limit:2)
+    * [ ] home task 1 (2015-08-01)  #{uuid}
+    * [ ] work task 1 (2015-08-01)  #{uuid}
+    """
+
+    tasks = [
+        dict(description="home task 1", project="Home", due=datetime(2015,8,1)),
+        dict(description="home task 2", project="Home", due=datetime(2015,8,2)),
+        dict(description="work task 1", project="Work", due=datetime(2015,8,1)),
+        dict(description="work task 2", project="Work", due=datetime(2015,8,2)),
+    ]
+
+    def execute(self):
+        # Generate the tasks
+        self.command("w", regex="written$", lines=1)
+
+
 class TestViewportsVisibleMetaTag(MultiSyntaxIntegrationTest):
 
     viminput = """

tests/test_viewport_parsing.py

@@ -112,6 +112,14 @@ class TestParsingVimwikiTask(object):
         assert port.sort == 'extra'
         assert port.tw == 'extra'
 
+    def test_count(self, test_syntax):
+        example_viewport = "HEADER2(Test | project:Home limit:2)"
+        port = self.process_viewport(example_viewport, test_syntax)
+
+        assert port.taskfilter == list(DEFAULT_VIEWPORT_VIRTUAL_TAGS) + ["(", "project:Home", ")"]
+        assert port.name == "Test"
+        assert port.count == 2
+
     def test_override_default_virtual_tags_neutral(self, test_syntax):
         example_viewport = "HEADER2(Test | project:Home !?DELETED)"
         port = self.process_viewport(example_viewport, test_syntax)