From 4945d262a021fc9eaa10016351dd4eca970ebea8 Mon Sep 17 00:00:00 2001
From: KV <kvid@users.noreply.github.com>
Date: Sun, 12 Sep 2021 23:19:44 +0200
Subject: [PATCH] Delete tweak.override attributes with null value

---
 docs/syntax.md             |  3 ++-
 src/wireviz/DataClasses.py |  2 +-
 src/wireviz/Harness.py     | 12 ++++++++++--
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/docs/syntax.md b/docs/syntax.md
index ce532b0..fa433c3 100644
--- a/docs/syntax.md
+++ b/docs/syntax.md
@@ -345,10 +345,11 @@ Alternatively items can be added to just the BOM by putting them in the section
     # Entries with an attribute containing HTML are
     # not supported.
     <str>:  # leading string of .gv entry
-      <str> : <str>  # attribute and its new value
+      <str> : <str/null>  # attribute and its new value
       # Any number of attributes can be overridden
       # for each entry. Attributes not already existing
       # in the entry will be appended to the entry.
+      # Use null as new value to delete an attribute.
 
   append: <str/list> # string or list of strings to append to the .gv output
 ```
diff --git a/src/wireviz/DataClasses.py b/src/wireviz/DataClasses.py
index c25b248..95325d1 100644
--- a/src/wireviz/DataClasses.py
+++ b/src/wireviz/DataClasses.py
@@ -61,7 +61,7 @@ class Options:
 
 @dataclass
 class Tweak:
-    override: Optional[Dict[Designator, Dict[str, str]]] = None
+    override: Optional[Dict[Designator, Dict[str, Optional[str]]]] = None
     append: Union[str, List[str], None] = None
 
 
diff --git a/src/wireviz/Harness.py b/src/wireviz/Harness.py
index 8e5a7f3..f4937f7 100644
--- a/src/wireviz/Harness.py
+++ b/src/wireviz/Harness.py
@@ -357,7 +357,7 @@ class Harness:
                 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)
+                    typecheck(f'tweak.override.{k}.{a} value', v, (str, type(None)))
 
             # Override generated attributes of selected entries matching tweak.override.
             for i, entry in enumerate(dot.body):
@@ -367,7 +367,14 @@ class Harness:
                     keyword = match and match[2]
                     if keyword in self.tweak.override.keys():
                         for attr, value in self.tweak.override[keyword].items():
-                            # TODO?: If value is None: delete attr?
+                            if value is None:
+                                entry, n_subs = re.subn(f'( +)?{attr}=("[^"]*"|[^] ]*)(?(1)| *)', '', entry)
+                                if n_subs < 1:
+                                    print(f'Harness.create_graph() warning: {attr} not found in {keyword}!')
+                                elif n_subs > 1:
+                                    print(f'Harness.create_graph() warning: {attr} removed {n_subs} times in {keyword}!')
+                                continue
+
                             if len(value) == 0 or ' ' in value:
                                 value = value.replace('"', r'\"')
                                 value = f'"{value}"'
@@ -377,6 +384,7 @@ class Harness:
                                 entry = re.sub(r'\]$', f' {attr}={value}]', entry)
                             elif n_subs > 1:
                                 print(f'Harness.create_graph() warning: {attr} overridden {n_subs} times in {keyword}!')
+
                         dot.body[i] = entry
 
         if self.tweak.append is not None: