Prettify sexpr to be as close to original KiCad format

Inspired by: mvnmgrx#123

Author: Wittmann-MEE

src/kiutils/board.py

@@ -25,6 +25,7 @@
 from kiutils.items.dimensions import Dimension
 from kiutils.utils.strings import dequote
 from kiutils.utils import sexpr
+from kiutils.utils.sexp_prettify import sexp_prettify as prettify
 from kiutils.footprint import Footprint
 from kiutils.misc.config import *
 
@@ -249,7 +250,8 @@ def to_file(self, filepath = None, encoding: Optional[str] = None):
             filepath = self.filePath
 
         with open(filepath, 'w', encoding=encoding) as outfile:
-            outfile.write(self.to_sexpr())
+            pre_formatted_sexpr = self.to_sexpr()
+            outfile.write(prettify(pre_formatted_sexpr))
 
     def to_sexpr(self, indent=0, newline=True) -> str:
         """Generate the S-Expression representing this object

src/kiutils/dru.py

@@ -20,6 +20,7 @@
 from os import path
 
 from kiutils.utils import sexpr
+from kiutils.utils.sexp_prettify import sexp_prettify as prettify
 from kiutils.utils.strings import dequote
 
 @dataclass
@@ -290,7 +291,8 @@ def to_file(self, filepath = None, encoding: Optional[str] = None):
             filepath = self.filePath
 
         with open(filepath, 'w', encoding=encoding) as outfile:
-            outfile.write(self.to_sexpr())
+            pre_formatted_sexpr = self.to_sexpr()
+            outfile.write(prettify(pre_formatted_sexpr))
 
     def to_sexpr(self, indent=0, newline=False):
         """Generate the S-Expression representing this object

src/kiutils/footprint.py

@@ -26,6 +26,7 @@
 from kiutils.items.fpitems import *
 from kiutils.items.gritems import *
 from kiutils.utils import sexpr
+from kiutils.utils.sexp_prettify import sexp_prettify as prettify
 from kiutils.utils.strings import dequote, remove_prefix
 from kiutils.misc.config import *
 
@@ -1028,7 +1029,8 @@ def to_file(self, filepath = None, encoding: Optional[str] = None):
             filepath = self.filePath
 
         with open(filepath, 'w', encoding=encoding) as outfile:
-            outfile.write(self.to_sexpr())
+            pre_formatted_sexpr = self.to_sexpr()
+            outfile.write(prettify(pre_formatted_sexpr))
 
     def to_sexpr(self, indent=0, newline=True, layerInFirstLine=False) -> str:
         """Generate the S-Expression representing this object

src/kiutils/libraries.py

@@ -18,6 +18,7 @@
 
 from kiutils.utils.strings import dequote
 from kiutils.utils import sexpr
+from kiutils.utils.sexp_prettify import sexp_prettify as prettify
 
 @dataclass
 class Library():
@@ -194,7 +195,8 @@ def to_file(self, filepath = None, encoding: Optional[str] = None):
             filepath = self.filePath
 
         with open(filepath, 'w', encoding=encoding) as outfile:
-            outfile.write(self.to_sexpr())
+            pre_formatted_sexpr = self.to_sexpr()
+            outfile.write(prettify(pre_formatted_sexpr))
 
     def to_sexpr(self, indent=0, newline=True) -> str:
         """Generate the S-Expression representing this object

src/kiutils/schematic.py

@@ -22,6 +22,7 @@
 from kiutils.items.schitems import *
 from kiutils.symbol import Symbol
 from kiutils.utils import sexpr
+from kiutils.utils.sexp_prettify import sexp_prettify as prettify
 from kiutils.misc.config import *
 
 @dataclass
@@ -240,7 +241,8 @@ def to_file(self, filepath = None, encoding: Optional[str] = None):
             filepath = self.filePath
 
         with open(filepath, 'w', encoding=encoding) as outfile:
-            outfile.write(self.to_sexpr())
+            pre_formatted_sexpr = self.to_sexpr()
+            outfile.write(prettify(pre_formatted_sexpr))
 
     def to_sexpr(self, indent=0, newline=True) -> str:
         """Generate the S-Expression representing this object

src/kiutils/symbol.py

@@ -20,6 +20,7 @@
 from kiutils.items.common import Property, Font
 from kiutils.items.syitems import *
 from kiutils.utils import sexpr
+from kiutils.utils.sexp_prettify import sexp_prettify as prettify
 from kiutils.utils.strings import dequote
 from kiutils.misc.config import *
 
@@ -589,7 +590,8 @@ def to_file(self, filepath = None, encoding: Optional[str] = None):
             filepath = self.filePath
 
         with open(filepath, 'w', encoding=encoding) as outfile:
-            outfile.write(self.to_sexpr())
+            pre_formatted_sexpr = self.to_sexpr()
+            outfile.write(prettify(pre_formatted_sexpr))
 
     def to_sexpr(self, indent: int = 0, newline: bool = True) -> str:
         """Generate the S-Expression representing this object

src/kiutils/utils/sexp_prettify.py

@@ -0,0 +1,186 @@
+"""
+Extracted from: https://github.com/mofosyne/sexp_prettify
+"""
+
+def sexp_prettify(source,
+             compact_save=False,
+             indent_char='\t',
+             indent_size=1,
+             consecutive_token_wrap_threshold=72,
+             compact_list_prefixes={"pts"},
+             compact_list_column_limit=99,
+             shortform_prefixes={"font", "stroke", "fill", "offset", "rotate", "scale", "teardrop"}):
+    """
+    Reformats KiCad-like S-expressions to match a specific formatting style.
+
+    Args:
+        source (str): The source S-expression string.
+        compact_save (bool): If True, enables compact mode formatting.
+
+    Returns:
+        str: The formatted S-expression.
+    """
+
+    # State tracking
+    formatted = []
+    list_depth = 0
+    column = 0
+    previous_non_space_output = ''
+    in_quote = False
+    escape_next_char = False
+    singular_element = False
+    space_pending = False
+    wrapped_list = False
+    scanning_for_prefix = False
+    prefix_token = ''
+    compact_list_mode = False
+    compact_list_indent = 0
+    shortform_mode = False
+    shortform_indent = 0
+
+    for c in source:
+
+        # Parse quoted strings
+        if c == '"' or in_quote:
+            if space_pending:
+                formatted.append(' ')
+                column += 1
+                space_pending = False
+
+            if escape_next_char:
+                escape_next_char = False
+            elif c == '\\':
+                escape_next_char = True
+            elif c == '"':
+                in_quote = not in_quote
+
+            formatted.append(c)
+            column += 1
+            previous_non_space_output = c
+            continue
+
+        # Parse spaces and newlines
+        if c.isspace():
+            space_pending = True
+
+            if scanning_for_prefix:
+                if prefix_token in compact_list_prefixes:
+                    compact_list_mode = True
+                    compact_list_indent = list_depth
+                elif compact_save and prefix_token in shortform_prefixes:
+                    shortform_mode = True
+                    shortform_indent = list_depth
+
+                scanning_for_prefix = False
+            continue
+
+        # Parse opening parentheses
+        if c == '(':
+            space_pending = False
+            if compact_list_mode:
+                # In fixed listDepth, visually compact mode
+                if column < compact_list_column_limit and previous_non_space_output == ')' or compact_list_column_limit == 0:
+                    # Is a consecutive list and still within column limit (or column limit disabled)
+                    formatted.append(' ')
+                    column += 1
+                else:
+                    # List is either beyond column limit or not after another list move this list to the next line
+                    formatted.append('\n')
+                    formatted.append(indent_char * compact_list_indent * indent_size)
+                    column = compact_list_indent * indent_size
+            elif shortform_mode:
+                # In one liner mode
+                formatted.append(' ')
+                column += 1
+            else:
+                # Start scanning for prefix for special list handling
+                scanning_for_prefix = True
+                prefix_token = ''
+                if list_depth > 0:
+                    # Print next line depth
+                    formatted.append('\n')
+                    formatted.append(indent_char * list_depth * indent_size)
+                    column = list_depth * indent_size
+
+            singular_element = True
+            list_depth += 1
+
+            formatted.append('(')
+            column += 1
+
+            previous_non_space_output = '('
+            continue
+
+        # Parse closing parentheses
+        if c == ')':
+            current_shortform_mode = shortform_mode
+            space_pending = False
+            scanning_for_prefix = False
+
+            if list_depth > 0:
+                list_depth -= 1
+
+            if compact_list_mode and list_depth < compact_list_indent:
+                compact_list_mode = False
+            if shortform_mode and list_depth < shortform_indent:
+                shortform_mode = False
+
+            if wrapped_list:
+                # This was a list with wrapped tokens so is already indented
+                formatted.append('\n')
+                formatted.append(indent_char * list_depth * indent_size)
+                column = list_depth * indent_size
+                if singular_element:
+                    singular_element = False
+                wrapped_list = False
+            else:
+                # Normal List
+                if singular_element:
+                    singular_element = False
+                elif not current_shortform_mode:
+                    formatted.append('\n')
+                    formatted.append(indent_char * list_depth * indent_size)
+                    column = list_depth * indent_size
+
+            formatted.append(')')
+            column += 1
+
+            if list_depth <= 0:
+                formatted.append('\n')
+                column = 0
+
+            previous_non_space_output = ')'
+            continue
+
+        # Parse characters
+        if c != '\0':
+            if previous_non_space_output == ')' and not shortform_mode:
+                # Is Bare token after a list that should be on next line
+                # Dev Note: In KiCAD this may indicate a flag bug
+                formatted.append('\n')
+                formatted.append(indent_char * list_depth * indent_size)
+                column = list_depth * indent_size
+                space_pending = False
+            elif space_pending and not shortform_mode and not compact_list_mode and column >= consecutive_token_wrap_threshold:
+                # Token is above wrap threshold. Move token to next line (If token wrap threshold is zero then this feature is disabled)
+                wrapped_list = True
+                formatted.append('\n')
+                formatted.append(indent_char * list_depth * indent_size)
+                column = list_depth * indent_size
+                space_pending = False
+            elif space_pending and previous_non_space_output != '(':
+                formatted.append(' ')
+                column += 1
+                space_pending = False
+
+            # Add to prefix scanning buffer if scanning for special list handling detection
+            if scanning_for_prefix:
+                prefix_token += c
+
+            # Add character to list
+            formatted.append(c)
+            column += 1
+            previous_non_space_output = c
+            continue
+
+    return ''.join(formatted)

src/kiutils/utils/sexpr.py

@@ -40,4 +40,4 @@ def parse_sexp(sexp):
         else:
             raise NotImplementedError("Error: (%r, %r)" % (term, value))
     assert not stack, "Trouble with nesting of brackets"
-    return out[0]
+    return out[0]

src/kiutils/wks.py

@@ -22,6 +22,7 @@
 from kiutils.items.common import Justify
 from kiutils.utils.strings import dequote
 from kiutils.utils import sexpr
+from kiutils.utils.sexp_prettify import sexp_prettify as prettify
 from kiutils.misc.config import KIUTILS_CREATE_NEW_GENERATOR_STR, KIUTILS_CREATE_NEW_VERSION_STR
 
 @dataclass
@@ -938,7 +939,8 @@ def to_file(self, filepath = None):
             filepath = self.filePath
 
         with open(filepath, 'w') as outfile:
-            outfile.write(self.to_sexpr())
+            pre_formatted_sexpr = self.to_sexpr()
+            outfile.write(prettify(pre_formatted_sexpr))
 
     def to_sexpr(self, indent=0, newline=True):
         """Generate the S-Expression representing this object