1 files changed, 174 insertions, 0 deletions
diff --git a/terminaltables3/build.py b/terminaltables3/build.py
new file mode 100644
index 0000000..c01349f
--- /dev/null
+++ b/terminaltables3/build.py
@@ -0,0 +1,174 @@
+"""Combine cells into rows."""
+
+from typing import Generator, Iterator, Optional, Sequence, Union
+
+from terminaltables3.width_and_alignment import visible_width
+
+
+def combine(
+    line: Union[
+        Generator[Union[int, str], None, None], Iterator[Optional[Union[int, str]]]
+    ],
+    left: str,
+    intersect: Optional[str],
+    right: str,
+) -> Generator[int, None, None]:
+    """Zip borders between items in `line`.
+
+    e.g. ('l', '1', 'c', '2', 'c', '3', 'r')
+
+    :param iter line: List to iterate.
+    :param left: Left border.
+    :param intersect: Column separator.
+    :param right: Right border.
+
+    :return: Yields combined objects.
+    """
+    # Yield left border.
+    if left:
+        yield left
+
+    # Yield items with intersect characters.
+    if intersect:
+        try:
+            for j, i in enumerate(line, start=-len(line) + 1):
+                yield i
+                if j:
+                    yield intersect
+        except TypeError:  # Generator.
+            try:
+                item = next(line)
+            except StopIteration:  # Was empty all along.
+                pass
+            else:
+                while True:
+                    yield item
+                    try:
+                        peek = next(line)
+                    except StopIteration:
+                        break
+                    yield intersect
+                    item = peek
+    else:
+        yield from line
+
+        # Yield right border.
+    if right:
+        yield right
+
+
+def build_border(
+    outer_widths: Sequence[int],
+    horizontal: str,
+    left: str,
+    intersect: str,
+    right: str,
+    title: Optional[str] = None,
+):
+    """Build the top/bottom/middle row. Optionally embed the table title within the border.
+
+    Title is hidden if it doesn't fit between the left/right characters/edges.
+
+    Example return value:
+    ('<', '-----', '+', '------', '+', '-------', '>')
+    ('<', 'My Table', '----', '+', '------->')
+
+    :param iter outer_widths: List of widths (with padding) for each column.
+    :param str horizontal: Character to stretch across each column.
+    :param str left: Left border.
+    :param str intersect: Column separator.
+    :param str right: Right border.
+    :param title: Overlay the title on the border between the left and right characters.
+
+    :return: Returns a generator of strings representing a border.
+    :rtype: iter
+    """
+    length = 0
+
+    # Hide title if it doesn't fit.
+    if title is not None and outer_widths:
+        try:
+            length = visible_width(title)
+        except TypeError:
+            title = str(title)
+            length = visible_width(title)
+        if length > sum(outer_widths) + len(intersect) * (len(outer_widths) - 1):
+            title = None
+
+    # Handle no title.
+    if title is None or not outer_widths or not horizontal:
+        return combine((horizontal * c for c in outer_widths), left, intersect, right)
+
+    # Handle title fitting in the first column.
+    if length == outer_widths[0]:
+        return combine(
+            [title] + [horizontal * c for c in outer_widths[1:]], left, intersect, right
+        )
+    if length < outer_widths[0]:
+        columns = [title + horizontal * (outer_widths[0] - length)] + [
+            horizontal * c for c in outer_widths[1:]
+        ]
+        return combine(columns, left, intersect, right)
+
+    # Handle wide titles/narrow columns.
+    columns_and_intersects = [title]
+    for width in combine(outer_widths, None, bool(intersect), None):
+        # If title is taken care of.
+        if length < 1:
+            columns_and_intersects.append(
+                intersect if width is True else horizontal * width
+            )
+        # If title's last character overrides an intersect character.
+        elif width is True and length == 1:
+            length = 0
+        # If this is an intersect character that is overridden by the title.
+        elif width is True:
+            length -= 1
+        # If title's last character is within a column.
+        elif width >= length:
+            columns_and_intersects[0] += horizontal * (
+                width - length
+            )  # Append horizontal chars to title.
+            length = 0
+        # If remainder of title won't fit in a column.
+        else:
+            length -= width
+
+    return combine(columns_and_intersects, left, None, right)
+
+
+def build_row(row, left, center, right):
+    """Combine single or multi-lined cells into a single row of list of lists including borders.
+
+    Row must already be padded and extended so each cell has the same number of lines.
+
+    Example return value:
+    [
+        ['>', 'Left ', '|', 'Center', '|', 'Right', '<'],
+        ['>', 'Cell1', '|', 'Cell2 ', '|', 'Cell3', '<'],
+    ]
+
+    :param iter row: List of cells for one row.
+    :param str left: Left border.
+    :param str center: Column separator.
+    :param str right: Right border.
+
+    :return: Yields other generators that yield strings.
+    :rtype: iter
+    """
+    if not row or not row[0]:
+        yield combine((), left, center, right)
+        return
+    for row_index in range(len(row[0])):
+        yield combine((c[row_index] for c in row), left, center, right)
+
+
+def flatten(table):
+    """Flatten table data into a single string with newlines.
+
+    :param iter table: Padded and bordered table data.
+
+    :return: Joined rows/cells.
+    :rtype: str
+    """
+    return "\n".join("".join(r) for r in table)