Add optional tweaking of the .gv output

Solves #174 intermediately by allowing low level .gv tweaking.

src/wireviz/DataClasses.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-from typing import Optional, List, Tuple, Union
+from typing import Dict, Optional, List, Tuple, Union
 from dataclasses import dataclass, field, InitVar
 from pathlib import Path
 
@@ -44,6 +44,12 @@ class Options:
     mini_bom_mode: bool = True
 
 
+@dataclass
+class Tweak:
+    override: Optional[Dict[Designator, Dict[str, str]]] = None
+    append: Union[str, List[str], None] = None
+
+
 @dataclass
 class Image:
     gv_dir: InitVar[Path] # Directory of .gv file injected as context during parsing

src/wireviz/Harness.py

@@ -10,7 +10,7 @@
 import re
 
 from wireviz import wv_colors, __version__, APP_NAME, APP_URL
-from wireviz.DataClasses import Metadata, Options, Connector, Cable
+from wireviz.DataClasses import Metadata, Options, Tweak, Connector, Cable
 from wireviz.wv_colors import get_color_hex, translate_color
 from wireviz.wv_gv_html import nested_html_table, html_colorbar, html_image, \
     html_caption, remove_links, html_line_breaks
@@ -25,6 +25,7 @@
 class Harness:
     metadata: Metadata
     options: Options
+    tweak: Tweak
 
     def __post_init__(self):
         self.connectors = {}
@@ -333,6 +334,44 @@ def create_graph(self) -> Graph:
             dot.node(cable.name, label=f'<\n{html}\n>', shape='box',
                      style='filled,dashed' if cable.category == 'bundle' else '', margin='0', fillcolor='white')
 
+        def typecheck(name: str, var, type) -> None:
+            if not isinstance(var, type):
+                raise Exception(f'Unexpected value type of {name}: {var}')
+
+        # TODO?: Differ between override attributes and HTML?
+        if self.tweak.override is not None:
+            typecheck('tweak.override', self.tweak.override, dict)
+            for k, d in self.tweak.override.items():
+                typecheck(f'tweak.override.{k} key', k, str)
+                typecheck(f'tweak.override.{k} value', d, dict)
+                for a, v in d.items():
+                    typecheck(f'tweak.override.{k}.{a} key', a, str)
+                    typecheck(f'tweak.override.{k}.{a} value', v, str)
+
+            # Override generated attributes of selected entries matching tweak.override.
+            for i, entry in enumerate(dot.body):
+                if isinstance(entry, str):
+                    # Find a possibly quoted keyword after leading TAB(s) and followed by [ ].
+                    match = re.match(r'^\t*(")?((?(1)[^"]|[^ "])+)(?(1)") \[.*\]$', entry, re.S)
+                    keyword = match and match[2]
+                    if keyword in self.tweak.override.keys():
+                        for attr, value in self.tweak.override[keyword].items():
+                            if len(value) == 0 or ' ' in value:
+                                value = value.replace('"', r'\"')
+                                value = f'"{value}"'
+                            # TODO?: If value is None: delete attr, and if attr not found: append it?
+                            entry = re.sub(f'{attr}=("[^"]*"|[^] ]*)', f'{attr}={value}', entry)
+                        dot.body[i] = entry
+
+        if self.tweak.append is not None:
+            if isinstance(self.tweak.append, list):
+                for i, element in enumerate(self.tweak.append, 1):
+                    typecheck(f'tweak.append[{i}]', element, str)
+                dot.body.extend(self.tweak.append)
+            else:
+                typecheck(f'tweak.append', self.tweak.append, str)
+                dot.body.append(self.tweak.append)
+
         return dot
 
     @property

src/wireviz/wireviz.py

@@ -13,7 +13,7 @@
     sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))
 
 from wireviz import __version__
-from wireviz.DataClasses import Metadata, Options
+from wireviz.DataClasses import Metadata, Options, Tweak
 from wireviz.Harness import Harness
 from wireviz.wv_helper import expand, open_file_read
 
@@ -39,6 +39,7 @@ def parse(yaml_input: str, file_out: (str, Path) = None, return_types: (None, st
     harness = Harness(
         Metadata(**{'title': Path(file_out).stem, **yaml_data.get('metadata', {})}),
         Options(**yaml_data.get('options', {})),
+        Tweak(**yaml_data.get('tweak', {})),
     )
 
     # add items