Add support for time code literals

Author: jonathanhogg

atom/language-flitter/grammars/flitter.cson

@@ -11,6 +11,10 @@ patterns: [
         match: '--.*$'
         name: 'comment.single.flitter'
     }
+    {
+        match: '\\b([0-9]+:)?[0-5]?[0-9]:[0-5]?[0-9](\\.[0-9]+)?\\b'
+        name: 'constant.timecode.flitter'
+    }
     {
         match: '\\b[-+]?([0-9][_0-9]*(\\.[0-9][_0-9]*)?|\\.[0-9][_0-9]*)([eE][-+]?[0-9][_0-9]*)?[pnuµmkMGT]?\\b'
         name: 'constant.numeric.flitter'

docs/language.md

@@ -238,6 +238,23 @@ symbol, then that symbol must be used to retrieve the state value. If a string
 has been used, then a symbol *cannot* be used to retrieve the value.
 :::
 
+### Time codes
+
+In addition to normal literal numbers, as described above, **Flitter** supports
+literal *time codes*, which are given as a sequence of hours, minutes and
+seconds separated with colon characters (`:`), with the hours being optional
+and the seconds having an optional decimal fraction. For example:
+
+```flitter
+!video filename='test.mp4' position=02:05.3
+```
+
+Time codes are converted by the parser into a single-item numeric vector
+representing the total number of seconds (*125.3* in the example above).
+The hours component may be an arbitrarily large integer value, the minutes
+and seconds must be in the range *[0,60)*. Time codes may not be combined with
+exponents or SI prefixes, and do not support `_` separators.
+
 ### Nodes
 
 The purpose of any **Flitter** program is to construct a render tree.

src/flitter/language/grammar.lark

@@ -11,6 +11,7 @@ NODE : /![_\p{alpha}][_\p{alnum}]*'*/i
 TAG : /#[_\p{alpha}][_\p{alnum}]*'*/i
 SYMBOL : /:[_\p{alpha}][_\p{alnum}]*'*/i
 NUMBER : /([0-9][_0-9]*(\.[0-9][_0-9]*)?|\.[0-9][_0-9]*)([eE][-+]?[0-9][_0-9]*)?[pnuµmkMGT]?/
+TIMECODE.2 : /([0-9]+:)?[0-5]?[0-9]:[0-5]?[0-9](\.[0-9]+)?/
 STRING : /('''([^'\\]|\\.|'{1,2}(?!'))*'''|'([^'\n\\]|\\.)*'|"""([^"\\]|\\.|"{1,2}(?!"))*"""|"([^"\n\\]|\\.)*")/
 _HASHBANG : /#!.*\r?\n/
 _LPAREN : "("
@@ -133,6 +134,7 @@ named_arg : NAME "=" node -> binding
       | _LPAREN node _RPAREN
 
 literal : NUMBER
+        | TIMECODE
         | STRING
         | SYMBOL
         | NODE

src/flitter/language/parser.py

@@ -56,6 +56,13 @@ def NUMBER(self, token):
             token = token[:-1]
         return model.Vector.coerce(float(token) * multiplier)
 
+    def TIMECODE(self, token):
+        parts = token.split(':')
+        seconds = 60*int(parts[-2]) + float(parts[-1])
+        if len(parts) == 3:
+            seconds += 3600*int(parts[-3])
+        return model.Vector.coerce(seconds)
+
     def TAG(self, token):
         return intern(str(token)[1:])