Improve WrappedPaginator performance on large text

jishaku/paginators.py

@@ -42,7 +42,7 @@ class WrappedPaginator(commands.Paginator):
     wrap_on: tuple
         A tuple of wrapping delimiters.
     include_wrapped: bool
-        Whether to include the delimiter at the start of the new wrapped line.
+        Whether to include the delimiter at the end of a wrapped line.
     force_wrap: bool
         If this is True, lines will be split at their maximum points should trimming not be possible
         with any provided delimiter.
@@ -55,39 +55,48 @@ def __init__(self, *args, wrap_on=('\n', ' '), include_wrapped=True, force_wrap=
         self.force_wrap = force_wrap
 
     def add_line(self, line='', *, empty=False):
-        true_max_size = self.max_size - self._prefix_len - self._suffix_len - 2
-        original_length = len(line)
+        if not empty:
+            true_max_size = self.max_size - self._prefix_len - self._suffix_len - 2
+            start = 0
+            needle = 0
+            last_delimiter = -1
+            last_space = -1
+
+            while needle < len(line):
+                if needle - start >= true_max_size:
+                    if last_delimiter != -1:
+                        if self.include_wrapped and line[last_delimiter] != '\n':
+                            super().add_line(line[start:last_delimiter + 1])
+                            needle = last_delimiter + 1
+                            start = last_delimiter + 1
+                        else:
+                            super().add_line(line[start:last_delimiter])
+                            needle = last_delimiter + 1
+                            start = last_delimiter + 1
+                    elif last_space != -1:
+                        super().add_line(line[start:last_space])
+                        needle = last_space + 1
+                        start = last_space
+                    else:
+                        super().add_line(line[start:needle])
+                        start = needle
 
-        while len(line) > true_max_size:
-            search_string = line[0:true_max_size - 1]
-            wrapped = False
+                    last_delimiter = -1
+                    last_space = -1
 
-            for delimiter in self.wrap_on:
-                position = search_string.rfind(delimiter)
+                if line[needle] in self.wrap_on:
+                    last_delimiter = needle
+                elif line[needle] == ' ':
+                    last_space = needle
 
-                if position > 0:
-                    super().add_line(line[0:position], empty=empty)
-                    wrapped = True
+                needle += 1
 
-                    if self.include_wrapped:
-                        line = line[position:]
-                    else:
-                        line = line[position + len(delimiter):]
-
-                    break
-
-            if not wrapped:
-                if self.force_wrap:
-                    super().add_line(line[0:true_max_size - 1])
-                    line = line[true_max_size - 1:]
-                else:
-                    raise ValueError(
-                        f"Line of length {original_length} had sequence of {len(line)} characters"
-                        f" (max is {true_max_size}) that WrappedPaginator could not wrap with"
-                        f" delimiters: {self.wrap_on}"
-                    )
-
-        super().add_line(line, empty=empty)
+            last_line = line[start:needle]
+            if last_line:
+                super().add_line(last_line)
+
+        else:
+            super().add_line(empty=empty)
 
 
 class FilePaginator(commands.Paginator):