Files
chatgpt-on-wechat/agent/tools/utils/truncate.py
2026-02-03 03:17:11 +08:00

293 lines
9.5 KiB
Python

"""
Shared truncation utilities for tool outputs.
Truncation is based on two independent limits - whichever is hit first wins:
- Line limit (default: 2000 lines)
- Byte limit (default: 50KB)
Never returns partial lines (except bash tail truncation edge case).
"""
from typing import Dict, Any, Optional, Literal, Tuple
DEFAULT_MAX_LINES = 2000
DEFAULT_MAX_BYTES = 50 * 1024 # 50KB
GREP_MAX_LINE_LENGTH = 500 # Max chars per grep match line
class TruncationResult:
"""Truncation result"""
def __init__(
self,
content: str,
truncated: bool,
truncated_by: Optional[Literal["lines", "bytes"]],
total_lines: int,
total_bytes: int,
output_lines: int,
output_bytes: int,
last_line_partial: bool = False,
first_line_exceeds_limit: bool = False,
max_lines: int = DEFAULT_MAX_LINES,
max_bytes: int = DEFAULT_MAX_BYTES
):
self.content = content
self.truncated = truncated
self.truncated_by = truncated_by
self.total_lines = total_lines
self.total_bytes = total_bytes
self.output_lines = output_lines
self.output_bytes = output_bytes
self.last_line_partial = last_line_partial
self.first_line_exceeds_limit = first_line_exceeds_limit
self.max_lines = max_lines
self.max_bytes = max_bytes
def to_dict(self) -> Dict[str, Any]:
"""Convert to dictionary"""
return {
"content": self.content,
"truncated": self.truncated,
"truncated_by": self.truncated_by,
"total_lines": self.total_lines,
"total_bytes": self.total_bytes,
"output_lines": self.output_lines,
"output_bytes": self.output_bytes,
"last_line_partial": self.last_line_partial,
"first_line_exceeds_limit": self.first_line_exceeds_limit,
"max_lines": self.max_lines,
"max_bytes": self.max_bytes
}
def format_size(bytes_count: int) -> str:
"""Format bytes as human-readable size"""
if bytes_count < 1024:
return f"{bytes_count}B"
elif bytes_count < 1024 * 1024:
return f"{bytes_count / 1024:.1f}KB"
else:
return f"{bytes_count / (1024 * 1024):.1f}MB"
def truncate_head(content: str, max_lines: Optional[int] = None, max_bytes: Optional[int] = None) -> TruncationResult:
"""
Truncate content from the head (keep first N lines/bytes).
Suitable for file reads where you want to see the beginning.
Never returns partial lines. If first line exceeds byte limit,
returns empty content with first_line_exceeds_limit=True.
:param content: Content to truncate
:param max_lines: Maximum number of lines (default: 2000)
:param max_bytes: Maximum number of bytes (default: 50KB)
:return: Truncation result
"""
if max_lines is None:
max_lines = DEFAULT_MAX_LINES
if max_bytes is None:
max_bytes = DEFAULT_MAX_BYTES
total_bytes = len(content.encode('utf-8'))
lines = content.split('\n')
total_lines = len(lines)
# Check if no truncation is needed
if total_lines <= max_lines and total_bytes <= max_bytes:
return TruncationResult(
content=content,
truncated=False,
truncated_by=None,
total_lines=total_lines,
total_bytes=total_bytes,
output_lines=total_lines,
output_bytes=total_bytes,
last_line_partial=False,
first_line_exceeds_limit=False,
max_lines=max_lines,
max_bytes=max_bytes
)
# Check if first line alone exceeds byte limit
first_line_bytes = len(lines[0].encode('utf-8'))
if first_line_bytes > max_bytes:
return TruncationResult(
content="",
truncated=True,
truncated_by="bytes",
total_lines=total_lines,
total_bytes=total_bytes,
output_lines=0,
output_bytes=0,
last_line_partial=False,
first_line_exceeds_limit=True,
max_lines=max_lines,
max_bytes=max_bytes
)
# Collect complete lines that fit
output_lines_arr = []
output_bytes_count = 0
truncated_by = "lines"
for i, line in enumerate(lines):
if i >= max_lines:
break
# Calculate line bytes (add 1 for newline if not first line)
line_bytes = len(line.encode('utf-8')) + (1 if i > 0 else 0)
if output_bytes_count + line_bytes > max_bytes:
truncated_by = "bytes"
break
output_lines_arr.append(line)
output_bytes_count += line_bytes
# If exited due to line limit
if len(output_lines_arr) >= max_lines and output_bytes_count <= max_bytes:
truncated_by = "lines"
output_content = '\n'.join(output_lines_arr)
final_output_bytes = len(output_content.encode('utf-8'))
return TruncationResult(
content=output_content,
truncated=True,
truncated_by=truncated_by,
total_lines=total_lines,
total_bytes=total_bytes,
output_lines=len(output_lines_arr),
output_bytes=final_output_bytes,
last_line_partial=False,
first_line_exceeds_limit=False,
max_lines=max_lines,
max_bytes=max_bytes
)
def truncate_tail(content: str, max_lines: Optional[int] = None, max_bytes: Optional[int] = None) -> TruncationResult:
"""
Truncate content from tail (keep last N lines/bytes).
Suitable for bash output where you want to see the ending content (errors, final results).
If the last line of original content exceeds byte limit, may return partial first line.
:param content: Content to truncate
:param max_lines: Maximum lines (default: 2000)
:param max_bytes: Maximum bytes (default: 50KB)
:return: Truncation result
"""
if max_lines is None:
max_lines = DEFAULT_MAX_LINES
if max_bytes is None:
max_bytes = DEFAULT_MAX_BYTES
total_bytes = len(content.encode('utf-8'))
lines = content.split('\n')
total_lines = len(lines)
# Check if no truncation is needed
if total_lines <= max_lines and total_bytes <= max_bytes:
return TruncationResult(
content=content,
truncated=False,
truncated_by=None,
total_lines=total_lines,
total_bytes=total_bytes,
output_lines=total_lines,
output_bytes=total_bytes,
last_line_partial=False,
first_line_exceeds_limit=False,
max_lines=max_lines,
max_bytes=max_bytes
)
# Work backwards from the end
output_lines_arr = []
output_bytes_count = 0
truncated_by = "lines"
last_line_partial = False
for i in range(len(lines) - 1, -1, -1):
if len(output_lines_arr) >= max_lines:
break
line = lines[i]
# Calculate line bytes (add newline if not the first added line)
line_bytes = len(line.encode('utf-8')) + (1 if len(output_lines_arr) > 0 else 0)
if output_bytes_count + line_bytes > max_bytes:
truncated_by = "bytes"
# Edge case: if we haven't added any lines yet and this line exceeds maxBytes,
# take the end portion of this line
if len(output_lines_arr) == 0:
truncated_line = _truncate_string_to_bytes_from_end(line, max_bytes)
output_lines_arr.insert(0, truncated_line)
output_bytes_count = len(truncated_line.encode('utf-8'))
last_line_partial = True
break
output_lines_arr.insert(0, line)
output_bytes_count += line_bytes
# If exited due to line limit
if len(output_lines_arr) >= max_lines and output_bytes_count <= max_bytes:
truncated_by = "lines"
output_content = '\n'.join(output_lines_arr)
final_output_bytes = len(output_content.encode('utf-8'))
return TruncationResult(
content=output_content,
truncated=True,
truncated_by=truncated_by,
total_lines=total_lines,
total_bytes=total_bytes,
output_lines=len(output_lines_arr),
output_bytes=final_output_bytes,
last_line_partial=last_line_partial,
first_line_exceeds_limit=False,
max_lines=max_lines,
max_bytes=max_bytes
)
def _truncate_string_to_bytes_from_end(text: str, max_bytes: int) -> str:
"""
Truncate string to fit byte limit (from end).
Properly handles multi-byte UTF-8 characters.
:param text: String to truncate
:param max_bytes: Maximum bytes
:return: Truncated string
"""
encoded = text.encode('utf-8')
if len(encoded) <= max_bytes:
return text
# Start from end, skip back maxBytes
start = len(encoded) - max_bytes
# Find valid UTF-8 boundary (character start)
while start < len(encoded) and (encoded[start] & 0xC0) == 0x80:
start += 1
return encoded[start:].decode('utf-8', errors='ignore')
def truncate_line(line: str, max_chars: int = GREP_MAX_LINE_LENGTH) -> Tuple[str, bool]:
"""
Truncate single line to max characters, add [truncated] suffix.
Used for grep match lines.
:param line: Line to truncate
:param max_chars: Maximum characters
:return: (truncated text, whether truncated)
"""
if len(line) <= max_chars:
return line, False
return f"{line[:max_chars]}... [truncated]", True