Add generic pagination utils

Author: linuxdaemon

cloudbot/util/pager.py

@@ -0,0 +1,73 @@
+from threading import RLock
+
+
+class Pager:
+    """Multiline pager
+
+    Takes a string with newlines and paginates it to certain size chunks
+    """
+
+    @classmethod
+    def from_multiline_string(cls, s):
+        return cls(s.splitlines())
+
+    def __init__(self, lines, chunk_size=2):
+        # This lock should always be acquired when accessing data from this object
+        # Added here due to extensive use of threads throughout plugins
+        self.lock = RLock()
+        self.chunk_size = chunk_size
+        self.chunks = tuple(
+            lines[i:i + self.chunk_size]
+            for i in range(0, len(lines), self.chunk_size)
+        )
+        self.current_pos = 0
+
+    def format_chunk(self, chunk, pagenum):
+        chunk = list(chunk)
+        if len(self.chunks) > 1:
+            chunk[-1] += " (page {}/{})".format(pagenum + 1, len(self.chunks))
+        return chunk
+
+    def next(self):
+        with self.lock:
+            if self.current_pos > len(self.chunks):
+                return None
+
+            chunk = self[self.current_pos]
+            self.current_pos += 1
+        return chunk
+
+    def get(self, index):
+        """Get a specific page"""
+        return self[index]
+
+    def __getitem__(self, item):
+        """Get a specific page"""
+        with self.lock:
+            chunk = self.chunks[item]
+            return self.format_chunk(chunk, item)
+
+    def __len__(self):
+        with self.lock:
+            return len(self.chunks)
+
+
+def paginated_list(data, delim=" \u2022 ", suffix='...', max_len=256, page_size=2):
+    lines = [""]
+    for item in data:
+        if len(item) > max_len:
+            # The length of a single item is longer then our max line length, split it
+            lines.append(item[:max_len])
+            lines.append(item[max_len:])
+        elif len(lines[-1]) + len(item) > max_len:
+            lines.append(item)
+        else:
+            if lines[-1]:
+                lines[-1] += delim
+
+            lines[-1] += item
+
+    formatted_lines = [
+        "{}{}".format(line, suffix) for line in lines
+    ]
+    return Pager(formatted_lines, chunk_size=page_size)