Feature appends prepends 1010 (#1015)

* Added appends, prepends filters, #1010

* Fixed initialization of field_arg

osxphotos/phototemplate.md

@@ -54,6 +54,8 @@ Valid filters are:
 - `join(x)`: Join list of values with delimiter x, e.g. join(,): ['a', 'b', 'c'] => 'a,b,c'; the DELIM option functions similar to join(x) but with DELIM, the join happens before being passed to any filters.May optionally be used without an argument, that is 'join()' which joins values together with no delimiter. e.g. join(): ['a', 'b', 'c'] => 'abc'.
 - `append(x)`: Append x to list of values, e.g. append(d): ['a', 'b', 'c'] => ['a', 'b', 'c', 'd'].
 - `prepend(x)`: Prepend x to list of values, e.g. prepend(d): ['a', 'b', 'c'] => ['d', 'a', 'b', 'c'].
+- `appends(x)`: [append s(tring)] Append x to each value of list of values, e.g. appends(d): ['a', 'b', 'c'] => ['ad', 'bd', 'cd'].
+- `prepends(x)`: [prepend s(tring)] Prepend x to each value of list of values, e.g. prepends(d): ['a', 'b', 'c'] => ['da', 'db', 'dc'].
 - `remove(x)`: Remove x from list of values, e.g. remove(b): ['a', 'b', 'c'] => ['a', 'c'].
 - `slice(start:stop:step)`: Slice list using same semantics as Python's list slicing, e.g. slice(1:3): ['a', 'b', 'c', 'd'] => ['b', 'c']; slice(1:4:2): ['a', 'b', 'c', 'd'] => ['b', 'd']; slice(1:): ['a', 'b', 'c', 'd'] => ['b', 'c', 'd']; slice(:-1): ['a', 'b', 'c', 'd'] => ['a', 'b', 'c']; slice(::-1): ['a', 'b', 'c', 'd'] => ['d', 'c', 'b', 'a']. See also sslice().
 - `sslice(start:stop:step)`: [s(tring) slice] Slice values in a list using same semantics as Python's string slicing, e.g. sslice(1:3):'abcd => 'bc'; sslice(1:4:2): 'abcd' => 'bd', etc. See also slice().

osxphotos/phototemplate.py

@@ -285,6 +285,8 @@ FILTER_VALUES = {
     + "e.g. join(): ['a', 'b', 'c'] => 'abc'.",
     "append(x)": "Append x to list of values, e.g. append(d): ['a', 'b', 'c'] => ['a', 'b', 'c', 'd'].",
     "prepend(x)": "Prepend x to list of values, e.g. prepend(d): ['a', 'b', 'c'] => ['d', 'a', 'b', 'c'].",
+    "appends(x)": "Append s[tring] Append x to each value of list of values, e.g. appends(d): ['a', 'b', 'c'] => ['ad', 'bd', 'cd'].",
+    "prepends(x)": "Prepend s[tring] x to each value of list of values, e.g. prepends(d): ['a', 'b', 'c'] => ['da', 'db', 'dc'].",
     "remove(x)": "Remove x from list of values, e.g. remove(b): ['a', 'b', 'c'] => ['a', 'c'].",
     "slice(start:stop:step)": "Slice list using same semantics as Python's list slicing, "
     + "e.g. slice(1:3): ['a', 'b', 'c', 'd'] => ['b', 'c']; slice(1:4:2): ['a', 'b', 'c', 'd'] => ['b', 'd']; "
@@ -543,6 +545,8 @@ class PhotoTemplate:
             # process field arguments
             if ts.template.fieldarg is not None:
                 field_arg = ts.template.fieldarg.value
+            else:
+                field_arg = None
 
             # process delim
             if ts.template.delim is not None:
@@ -1007,15 +1011,17 @@ class PhotoTemplate:
             raise SyntaxError(f"Unknown filter: {filter_}")
 
         if filter_ in [
-            "split",
-            "chop",
-            "chomp",
             "append",
+            "appends",
+            "chomp",
+            "chop",
+            "filter",
             "prepend",
+            "prepends",
             "remove",
             "slice",
+            "split",
             "sslice",
-            "filter",
         ] and (args is None or not len(args)):
             raise SyntaxError(f"{filter_} requires arguments")
 
@@ -1032,15 +1038,13 @@ class PhotoTemplate:
         elif filter_ == "braces":
             value = ["{" + v + "}" for v in values]
         elif filter_ == "parens":
-            value = ["(" + v + ")" for v in values]
+            value = [f"({v})" for v in values]
         elif filter_ == "brackets":
-            value = ["[" + v + "]" for v in values]
+            value = [f"[{v}]" for v in values]
         elif filter_ == "shell_quote":
             value = [shlex.quote(v) for v in values]
         elif filter_ == "split":
-            # split on delimiter
+            if delim := args:
-            delim = args
-            if delim:
                 new_values = []
                 for v in values:
                     new_values.extend(v.split(delim))
@@ -1051,15 +1055,15 @@ class PhotoTemplate:
             # chop off characters from the end
             try:
                 chop = int(args)
-            except ValueError:
+            except ValueError as e:
-                raise SyntaxError(f"Invalid value for chop: {args}")
+                raise SyntaxError(f"Invalid value for chop: {args}") from e
             value = [v[:-chop] for v in values] if chop else values
         elif filter_ == "chomp":
             # chop off characters from the beginning
             try:
                 chomp = int(args)
-            except ValueError:
+            except ValueError as e:
-                raise SyntaxError(f"Invalid value for chomp: {args}")
+                raise SyntaxError(f"Invalid value for chomp: {args}") from e
             value = [v[chomp:] for v in values] if chomp else values
         elif filter_ == "autosplit":
             # try to split keyword strings automatically
@@ -1094,6 +1098,12 @@ class PhotoTemplate:
         elif filter_ == "prepend":
             # prepend value to list
             value = [args] + values
+        elif filter_ == "appends":
+            # append value to each item in list
+            value = [f"{v}{args}" for v in values]
+        elif filter_ == "prepends":
+            # prepend value to each item in list
+            value = [f"{args}{v}" for v in values]
         elif filter_ == "remove":
             # remove value from list
             value = [v for v in values if v != args]

tests/test_template.py

@@ -78,11 +78,15 @@ TEMPLATE_VALUES_MULTI_KEYWORDS = {
     "{; +keyword}": ["flowers; wedding"],
     "{; +keyword|titlecase}": ["Flowers; Wedding"],
     "{; +keyword|titlecase|parens}": ["(Flowers; Wedding)"],
+    "{keyword|appends(:keyword)}": ["flowers:keyword", "wedding:keyword"],
+    "{keyword|prepends(keyword:)}": ["keyword:flowers", "keyword:wedding"],
 }
 
 UUID_TITLE = "6191423D-8DB8-4D4C-92BE-9BBBA308AAC4"
 TEMPLATE_VALUES_TITLE = {
     "{title}": ["Tulips tied together at a flower shop"],
+    "{title|appends(:title)}": ["Tulips tied together at a flower shop:title"],
+    "{title|prepends(title:)}": ["title:Tulips tied together at a flower shop"],
     "{title|titlecase}": ["Tulips Tied Together At A Flower Shop"],
     "{title|upper}": ["TULIPS TIED TOGETHER AT A FLOWER SHOP"],
     "{title|titlecase|lower|upper}": ["TULIPS TIED TOGETHER AT A FLOWER SHOP"],