Files
hermes-agent/tools/fuzzy_match.py
teknium1 ea95462998 fix(tools): browser handler safety + fuzzy_match docstring accuracy
1. browser_tool.py: Replace **args spread on browser_click, browser_type,
   and browser_scroll handlers with explicit parameter extraction. The
   **args pattern passed all dict keys as keyword arguments, causing
   TypeError if the LLM sent unexpected parameters. Now extracts only
   the expected params (ref, text, direction) with safe defaults.

2. fuzzy_match.py: Update module docstring to match actual strategy
   order in code. Block anchor was listed as #3 but is actually #7.
   Multi-occurrence is not a separate strategy but a flag. Updated
   count from 9 to 8.
2026-03-17 04:32:39 -07:00

488 lines
17 KiB
Python

#!/usr/bin/env python3
"""
Fuzzy Matching Module for File Operations
Implements a multi-strategy matching chain to robustly find and replace text,
accommodating variations in whitespace, indentation, and escaping common
in LLM-generated code.
The 8-strategy chain (inspired by OpenCode), tried in order:
1. Exact match - Direct string comparison
2. Line-trimmed - Strip leading/trailing whitespace per line
3. Whitespace normalized - Collapse multiple spaces/tabs to single space
4. Indentation flexible - Ignore indentation differences entirely
5. Escape normalized - Convert \\n literals to actual newlines
6. Trimmed boundary - Trim first/last line whitespace only
7. Block anchor - Match first+last lines, use similarity for middle
8. Context-aware - 50% line similarity threshold
Multi-occurrence matching is handled via the replace_all flag.
Usage:
from tools.fuzzy_match import fuzzy_find_and_replace
new_content, match_count, error = fuzzy_find_and_replace(
content="def foo():\\n pass",
old_string="def foo():",
new_string="def bar():",
replace_all=False
)
"""
import re
from typing import Tuple, Optional, List, Callable
from difflib import SequenceMatcher
UNICODE_MAP = {
"\u201c": '"', "\u201d": '"', # smart double quotes
"\u2018": "'", "\u2019": "'", # smart single quotes
"\u2014": "--", "\u2013": "-", # em/en dashes
"\u2026": "...", "\u00a0": " ", # ellipsis and non-breaking space
}
def _unicode_normalize(text: str) -> str:
"""Normalizes Unicode characters to their standard ASCII equivalents."""
for char, repl in UNICODE_MAP.items():
text = text.replace(char, repl)
return text
def fuzzy_find_and_replace(content: str, old_string: str, new_string: str,
replace_all: bool = False) -> Tuple[str, int, Optional[str]]:
"""
Find and replace text using a chain of increasingly fuzzy matching strategies.
Args:
content: The file content to search in
old_string: The text to find
new_string: The replacement text
replace_all: If True, replace all occurrences; if False, require uniqueness
Returns:
Tuple of (new_content, match_count, error_message)
- If successful: (modified_content, number_of_replacements, None)
- If failed: (original_content, 0, error_description)
"""
if not old_string:
return content, 0, "old_string cannot be empty"
if old_string == new_string:
return content, 0, "old_string and new_string are identical"
# Try each matching strategy in order
strategies: List[Tuple[str, Callable]] = [
("exact", _strategy_exact),
("line_trimmed", _strategy_line_trimmed),
("whitespace_normalized", _strategy_whitespace_normalized),
("indentation_flexible", _strategy_indentation_flexible),
("escape_normalized", _strategy_escape_normalized),
("trimmed_boundary", _strategy_trimmed_boundary),
("block_anchor", _strategy_block_anchor),
("context_aware", _strategy_context_aware),
]
for strategy_name, strategy_fn in strategies:
matches = strategy_fn(content, old_string)
if matches:
# Found matches with this strategy
if len(matches) > 1 and not replace_all:
return content, 0, (
f"Found {len(matches)} matches for old_string. "
f"Provide more context to make it unique, or use replace_all=True."
)
# Perform replacement
new_content = _apply_replacements(content, matches, new_string)
return new_content, len(matches), None
# No strategy found a match
return content, 0, "Could not find a match for old_string in the file"
def _apply_replacements(content: str, matches: List[Tuple[int, int]], new_string: str) -> str:
"""
Apply replacements at the given positions.
Args:
content: Original content
matches: List of (start, end) positions to replace
new_string: Replacement text
Returns:
Content with replacements applied
"""
# Sort matches by position (descending) to replace from end to start
# This preserves positions of earlier matches
sorted_matches = sorted(matches, key=lambda x: x[0], reverse=True)
result = content
for start, end in sorted_matches:
result = result[:start] + new_string + result[end:]
return result
# =============================================================================
# Matching Strategies
# =============================================================================
def _strategy_exact(content: str, pattern: str) -> List[Tuple[int, int]]:
"""Strategy 1: Exact string match."""
matches = []
start = 0
while True:
pos = content.find(pattern, start)
if pos == -1:
break
matches.append((pos, pos + len(pattern)))
start = pos + 1
return matches
def _strategy_line_trimmed(content: str, pattern: str) -> List[Tuple[int, int]]:
"""
Strategy 2: Match with line-by-line whitespace trimming.
Strips leading/trailing whitespace from each line before matching.
"""
# Normalize pattern and content by trimming each line
pattern_lines = [line.strip() for line in pattern.split('\n')]
pattern_normalized = '\n'.join(pattern_lines)
content_lines = content.split('\n')
content_normalized_lines = [line.strip() for line in content_lines]
# Build mapping from normalized positions back to original positions
return _find_normalized_matches(
content, content_lines, content_normalized_lines,
pattern, pattern_normalized
)
def _strategy_whitespace_normalized(content: str, pattern: str) -> List[Tuple[int, int]]:
"""
Strategy 3: Collapse multiple whitespace to single space.
"""
def normalize(s):
# Collapse multiple spaces/tabs to single space, preserve newlines
return re.sub(r'[ \t]+', ' ', s)
pattern_normalized = normalize(pattern)
content_normalized = normalize(content)
# Find in normalized, map back to original
matches_in_normalized = _strategy_exact(content_normalized, pattern_normalized)
if not matches_in_normalized:
return []
# Map positions back to original content
return _map_normalized_positions(content, content_normalized, matches_in_normalized)
def _strategy_indentation_flexible(content: str, pattern: str) -> List[Tuple[int, int]]:
"""
Strategy 4: Ignore indentation differences entirely.
Strips all leading whitespace from lines before matching.
"""
def strip_indent(s):
return '\n'.join(line.lstrip() for line in s.split('\n'))
pattern_stripped = strip_indent(pattern)
content_lines = content.split('\n')
content_stripped_lines = [line.lstrip() for line in content_lines]
pattern_lines = [line.lstrip() for line in pattern.split('\n')]
return _find_normalized_matches(
content, content_lines, content_stripped_lines,
pattern, '\n'.join(pattern_lines)
)
def _strategy_escape_normalized(content: str, pattern: str) -> List[Tuple[int, int]]:
"""
Strategy 5: Convert escape sequences to actual characters.
Handles \\n -> newline, \\t -> tab, etc.
"""
def unescape(s):
# Convert common escape sequences
return s.replace('\\n', '\n').replace('\\t', '\t').replace('\\r', '\r')
pattern_unescaped = unescape(pattern)
if pattern_unescaped == pattern:
# No escapes to convert, skip this strategy
return []
return _strategy_exact(content, pattern_unescaped)
def _strategy_trimmed_boundary(content: str, pattern: str) -> List[Tuple[int, int]]:
"""
Strategy 6: Trim whitespace from first and last lines only.
Useful when the pattern boundaries have whitespace differences.
"""
pattern_lines = pattern.split('\n')
if not pattern_lines:
return []
# Trim only first and last lines
pattern_lines[0] = pattern_lines[0].strip()
if len(pattern_lines) > 1:
pattern_lines[-1] = pattern_lines[-1].strip()
modified_pattern = '\n'.join(pattern_lines)
content_lines = content.split('\n')
# Search through content for matching block
matches = []
pattern_line_count = len(pattern_lines)
for i in range(len(content_lines) - pattern_line_count + 1):
block_lines = content_lines[i:i + pattern_line_count]
# Trim first and last of this block
check_lines = block_lines.copy()
check_lines[0] = check_lines[0].strip()
if len(check_lines) > 1:
check_lines[-1] = check_lines[-1].strip()
if '\n'.join(check_lines) == modified_pattern:
# Found match - calculate original positions
start_pos, end_pos = _calculate_line_positions(
content_lines, i, i + pattern_line_count, len(content)
)
matches.append((start_pos, end_pos))
return matches
def _strategy_block_anchor(content: str, pattern: str) -> List[Tuple[int, int]]:
"""
Strategy 7: Match by anchoring on first and last lines.
Adjusted with permissive thresholds and unicode normalization.
"""
# Normalize both strings for comparison while keeping original content for offset calculation
norm_pattern = _unicode_normalize(pattern)
norm_content = _unicode_normalize(content)
pattern_lines = norm_pattern.split('\n')
if len(pattern_lines) < 2:
return []
first_line = pattern_lines[0].strip()
last_line = pattern_lines[-1].strip()
# Use normalized lines for matching logic
norm_content_lines = norm_content.split('\n')
# BUT use original lines for calculating start/end positions to prevent index shift
orig_content_lines = content.split('\n')
pattern_line_count = len(pattern_lines)
potential_matches = []
for i in range(len(norm_content_lines) - pattern_line_count + 1):
if (norm_content_lines[i].strip() == first_line and
norm_content_lines[i + pattern_line_count - 1].strip() == last_line):
potential_matches.append(i)
matches = []
candidate_count = len(potential_matches)
# Thresholding logic: 0.10 for unique matches (max flexibility), 0.30 for multiple candidates
threshold = 0.10 if candidate_count == 1 else 0.30
for i in potential_matches:
if pattern_line_count <= 2:
similarity = 1.0
else:
# Compare normalized middle sections
content_middle = '\n'.join(norm_content_lines[i+1:i+pattern_line_count-1])
pattern_middle = '\n'.join(pattern_lines[1:-1])
similarity = SequenceMatcher(None, content_middle, pattern_middle).ratio()
if similarity >= threshold:
# Calculate positions using ORIGINAL lines to ensure correct character offsets in the file
start_pos, end_pos = _calculate_line_positions(
orig_content_lines, i, i + pattern_line_count, len(content)
)
matches.append((start_pos, end_pos))
return matches
def _strategy_context_aware(content: str, pattern: str) -> List[Tuple[int, int]]:
"""
Strategy 8: Line-by-line similarity with 50% threshold.
Finds blocks where at least 50% of lines have high similarity.
"""
pattern_lines = pattern.split('\n')
content_lines = content.split('\n')
if not pattern_lines:
return []
matches = []
pattern_line_count = len(pattern_lines)
for i in range(len(content_lines) - pattern_line_count + 1):
block_lines = content_lines[i:i + pattern_line_count]
# Calculate line-by-line similarity
high_similarity_count = 0
for p_line, c_line in zip(pattern_lines, block_lines):
sim = SequenceMatcher(None, p_line.strip(), c_line.strip()).ratio()
if sim >= 0.80:
high_similarity_count += 1
# Need at least 50% of lines to have high similarity
if high_similarity_count >= len(pattern_lines) * 0.5:
start_pos, end_pos = _calculate_line_positions(
content_lines, i, i + pattern_line_count, len(content)
)
matches.append((start_pos, end_pos))
return matches
# =============================================================================
# Helper Functions
# =============================================================================
def _calculate_line_positions(content_lines: List[str], start_line: int,
end_line: int, content_length: int) -> Tuple[int, int]:
"""Calculate start and end character positions from line indices.
Args:
content_lines: List of lines (without newlines)
start_line: Starting line index (0-based)
end_line: Ending line index (exclusive, 0-based)
content_length: Total length of the original content string
Returns:
Tuple of (start_pos, end_pos) in the original content
"""
start_pos = sum(len(line) + 1 for line in content_lines[:start_line])
end_pos = sum(len(line) + 1 for line in content_lines[:end_line]) - 1
if end_pos >= content_length:
end_pos = content_length
return start_pos, end_pos
def _find_normalized_matches(content: str, content_lines: List[str],
content_normalized_lines: List[str],
pattern: str, pattern_normalized: str) -> List[Tuple[int, int]]:
"""
Find matches in normalized content and map back to original positions.
Args:
content: Original content string
content_lines: Original content split by lines
content_normalized_lines: Normalized content lines
pattern: Original pattern
pattern_normalized: Normalized pattern
Returns:
List of (start, end) positions in the original content
"""
pattern_norm_lines = pattern_normalized.split('\n')
num_pattern_lines = len(pattern_norm_lines)
matches = []
for i in range(len(content_normalized_lines) - num_pattern_lines + 1):
# Check if this block matches
block = '\n'.join(content_normalized_lines[i:i + num_pattern_lines])
if block == pattern_normalized:
# Found a match - calculate original positions
start_pos, end_pos = _calculate_line_positions(
content_lines, i, i + num_pattern_lines, len(content)
)
matches.append((start_pos, end_pos))
return matches
def _map_normalized_positions(original: str, normalized: str,
normalized_matches: List[Tuple[int, int]]) -> List[Tuple[int, int]]:
"""
Map positions from normalized string back to original.
This is a best-effort mapping that works for whitespace normalization.
"""
if not normalized_matches:
return []
# Build character mapping from normalized to original
orig_to_norm = [] # orig_to_norm[i] = position in normalized
orig_idx = 0
norm_idx = 0
while orig_idx < len(original) and norm_idx < len(normalized):
if original[orig_idx] == normalized[norm_idx]:
orig_to_norm.append(norm_idx)
orig_idx += 1
norm_idx += 1
elif original[orig_idx] in ' \t' and normalized[norm_idx] == ' ':
# Original has space/tab, normalized collapsed to space
orig_to_norm.append(norm_idx)
orig_idx += 1
# Don't advance norm_idx yet - wait until all whitespace consumed
if orig_idx < len(original) and original[orig_idx] not in ' \t':
norm_idx += 1
elif original[orig_idx] in ' \t':
# Extra whitespace in original
orig_to_norm.append(norm_idx)
orig_idx += 1
else:
# Mismatch - shouldn't happen with our normalization
orig_to_norm.append(norm_idx)
orig_idx += 1
# Fill remaining
while orig_idx < len(original):
orig_to_norm.append(len(normalized))
orig_idx += 1
# Reverse mapping: for each normalized position, find original range
norm_to_orig_start = {}
norm_to_orig_end = {}
for orig_pos, norm_pos in enumerate(orig_to_norm):
if norm_pos not in norm_to_orig_start:
norm_to_orig_start[norm_pos] = orig_pos
norm_to_orig_end[norm_pos] = orig_pos
# Map matches
original_matches = []
for norm_start, norm_end in normalized_matches:
# Find original start
if norm_start in norm_to_orig_start:
orig_start = norm_to_orig_start[norm_start]
else:
# Find nearest
orig_start = min(i for i, n in enumerate(orig_to_norm) if n >= norm_start)
# Find original end
if norm_end - 1 in norm_to_orig_end:
orig_end = norm_to_orig_end[norm_end - 1] + 1
else:
orig_end = orig_start + (norm_end - norm_start)
# Expand to include trailing whitespace that was normalized
while orig_end < len(original) and original[orig_end] in ' \t':
orig_end += 1
original_matches.append((orig_start, min(orig_end, len(original))))
return original_matches