From d0ece455dad6eb3b11f412d6baca340676920f9d Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Sun, 10 Nov 2019 16:44:59 +0000
Subject: [PATCH] tidier rich text

---
 rich/text.py | 69 +++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 50 insertions(+), 19 deletions(-)

diff --git a/rich/text.py b/rich/text.py
index 8a67fa83..a5ceb95e 100644
--- a/rich/text.py
+++ b/rich/text.py
@@ -13,9 +13,9 @@ class TextSpan(NamedTuple):
 
     start: int
     end: int
-    style: Optional[str]
+    style: str
 
-    def adjust_offset(self, offset: int) -> TextSpan:
+    def adjust_offset(self, offset: int, max_length) -> TextSpan:
         """Get a new `TextSpan` with start and end adjusted.
         
         Args:
@@ -24,7 +24,11 @@ class TextSpan(NamedTuple):
         Returns:
             TextSpan: A new text span.
         """
-        return TextSpan(self.start + offset, self.end + offset, self.style)
+        return TextSpan(
+            min(max_length, max(0, self.start + offset)),
+            min(max_length, max(0, self.end + offset)),
+            self.style,
+        )
 
     def slice_text(self, text: str) -> str:
         """Slice the text according to the start and end offsets.
@@ -59,32 +63,59 @@ class RichText:
         return f"RichText({self.text!r})"
 
     def stylize(self, start: int, end: int, style: str) -> None:
-        self._spans.append(TextSpan(start, end, style))
+        """Apply a style to a portion of the text.
+        
+        Args:
+            start (int): Start offset.
+            end (int): End offset.
+            style (str): Style name to apply.
+        
+        Returns:
+            None: 
+        """
+        length = len(self)
+        if end < 0 or start > length:
+            # span in range
+            return
+        self._spans.append(TextSpan(max(0, start), min(length, end), style))
 
     def __console_render__(
         self, console: Console, options: ConsoleOptions
     ) -> Iterable[StyledText]:
+        """Render the rich text to the console.
+        
+        Args:
+            console (Console): Console instance.
+            options (ConsoleOptions): Console options.
+        
+        Returns:
+            Iterable[StyledText]: An iterable of styled text.
+        """
 
-        print(self._spans)
         text = self.text
         stack: List[Style] = []
 
         get_style = console.get_style
-        spans = [
-            (span.start, True, get_style(span.style or "none")) for span in self._spans
-        ]
-        spans.extend(
-            (span.end, False, get_style(span.style or "none")) for span in self._spans
-        )
-        spans.sort(key=itemgetter(0))
-        spans.insert(0, (0, True, get_style("none")))
-        spans.append((len(text), False, get_style("none")))
-
         null_style = Style()
-        current_style = Style()
+        start_spans = (
+            (span.start, True, get_style(span.style) or null_style)
+            for span in self._spans
+        )
+        end_spans = (
+            (span.end, False, get_style(span.style) or null_style)
+            for span in self._spans
+        )
 
+        spans = [
+            (0, True, null_style),
+            *start_spans,
+            *end_spans,
+            (len(text), False, null_style),
+        ]
+        spans.sort(key=itemgetter(0))
+
+        current_style = Style()
         for (offset, entering, style), (next_offset, _, _) in zip(spans, spans[1:]):
-            style = style or null_style
             if entering:
                 stack.append(style)
                 current_style = current_style.apply(style)
@@ -113,7 +144,7 @@ class RichText:
         self._text.append(text)
         offset = len(self)
         text_length = len(text)
-        self._spans.append(TextSpan(offset, offset + text_length, style))
+        self._spans.append(TextSpan(offset, offset + text_length, style or "none"))
         self._length += text_length
         self._text_str = None
 
@@ -131,7 +162,7 @@ class RichText:
             for offset, line in zip(offsets, new_lines):
                 if span.end <= offset or span.start >= offset + len(line):
                     continue
-                line._spans.append(span.adjust_offset(-offset))
+                line._spans.append(span.adjust_offset(-offset, len(line)))
 
         return new_lines