Wordwrap: prevent infinite loop + cache result

Previously a line that was too long but didn't contain spaces would cause
an infinite loop and hang Blender. Now we just hard-break each line when
there are no spaces to be found.

The result of word_wrap() is now also cached, so that redraws are more
efficient.

benchmark/space/draw.py

@@ -1,3 +1,4 @@
+import functools
 import os.path
 
 import blf
@@ -249,15 +250,18 @@ def _after_submission_text() -> str:
     return text
 
 
-def word_wrap(string: str, width_in_px: int) -> str:
+@functools.lru_cache()
+def word_wrap(string: str, width_in_px: int, *, depth=0) -> str:
     """Word-wrapping with variable character width.
 
     Newlines in the input string are kept in the output.
     """
 
+    assert depth < 3
+
     if '\n' in string:
         # If the string already consists of multiple lines, wrap each line individually.
-        return '\n'.join(word_wrap(line, width_in_px)
+        return '\n'.join(word_wrap(line, width_in_px, depth=depth + 1)
                          for line in string.splitlines(keepends=False))
 
     # Do an estimate of the maximum number of characters to fit on a line.
@@ -271,10 +275,19 @@ def word_wrap(string: str, width_in_px: int) -> str:
         line_width = blf.dimensions(font_id, candidate_line)[0]
 
         # Keep removing the last word until the line fits the width.
-        while line_width >= width_in_px:
-            marker = len(candidate_line) - 1
-            while not candidate_line[marker].isspace():
-                marker -= 1
+        break_at_space = True
+        while candidate_line and line_width >= width_in_px:
+            if break_at_space:
+                marker = len(candidate_line) - 1
+                while marker > 0 and not candidate_line[marker].isspace():
+                    marker -= 1
+                if marker <= 0:
+                    # This line was unbreakable by whitespace. Let's just hard-break it.
+                    break_at_space = False
+                    continue
+            else:
+                marker = len(candidate_line) - 1
+
             candidate_line = candidate_line[:marker]
             line_width = blf.dimensions(font_id, candidate_line)[0]