1 files changed, 98 insertions, 0 deletions
diff --git a/src/prompt_toolkit/formatted_text/utils.py b/src/prompt_toolkit/formatted_text/utils.py
new file mode 100644
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+++ b/src/prompt_toolkit/formatted_text/utils.py
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+"""
+Utilities for manipulating formatted text.
+
+When ``to_formatted_text`` has been called, we get a list of ``(style, text)``
+tuples. This file contains functions for manipulating such a list.
+"""
+from typing import Iterable, cast
+
+from prompt_toolkit.utils import get_cwidth
+
+from .base import (
+    AnyFormattedText,
+    OneStyleAndTextTuple,
+    StyleAndTextTuples,
+    to_formatted_text,
+)
+
+__all__ = [
+    "to_plain_text",
+    "fragment_list_len",
+    "fragment_list_width",
+    "fragment_list_to_text",
+    "split_lines",
+]
+
+
+def to_plain_text(value: AnyFormattedText) -> str:
+    """
+    Turn any kind of formatted text back into plain text.
+    """
+    return fragment_list_to_text(to_formatted_text(value))
+
+
+def fragment_list_len(fragments: StyleAndTextTuples) -> int:
+    """
+    Return the amount of characters in this text fragment list.
+
+    :param fragments: List of ``(style_str, text)`` or
+        ``(style_str, text, mouse_handler)`` tuples.
+    """
+    ZeroWidthEscape = "[ZeroWidthEscape]"
+    return sum(len(item[1]) for item in fragments if ZeroWidthEscape not in item[0])
+
+
+def fragment_list_width(fragments: StyleAndTextTuples) -> int:
+    """
+    Return the character width of this text fragment list.
+    (Take double width characters into account.)
+
+    :param fragments: List of ``(style_str, text)`` or
+        ``(style_str, text, mouse_handler)`` tuples.
+    """
+    ZeroWidthEscape = "[ZeroWidthEscape]"
+    return sum(
+        get_cwidth(c)
+        for item in fragments
+        for c in item[1]
+        if ZeroWidthEscape not in item[0]
+    )
+
+
+def fragment_list_to_text(fragments: StyleAndTextTuples) -> str:
+    """
+    Concatenate all the text parts again.
+
+    :param fragments: List of ``(style_str, text)`` or
+        ``(style_str, text, mouse_handler)`` tuples.
+    """
+    ZeroWidthEscape = "[ZeroWidthEscape]"
+    return "".join(item[1] for item in fragments if ZeroWidthEscape not in item[0])
+
+
+def split_lines(fragments: StyleAndTextTuples) -> Iterable[StyleAndTextTuples]:
+    """
+    Take a single list of (style_str, text) tuples and yield one such list for each
+    line. Just like str.split, this will yield at least one item.
+
+    :param fragments: List of (style_str, text) or (style_str, text, mouse_handler)
+                      tuples.
+    """
+    line: StyleAndTextTuples = []
+
+    for style, string, *mouse_handler in fragments:
+        parts = string.split("\n")
+
+        for part in parts[:-1]:
+            if part:
+                line.append(cast(OneStyleAndTextTuple, (style, part, *mouse_handler)))
+            yield line
+            line = []
+
+        line.append(cast(OneStyleAndTextTuple, (style, parts[-1], *mouse_handler)))
+
+    # Always yield the last line, even when this is an empty line. This ensures
+    # that when `fragments` ends with a newline character, an additional empty
+    # line is yielded. (Otherwise, there's no way to differentiate between the
+    # cases where `fragments` does and doesn't end with a newline.)
+    yield line