Allows hardcoding sequences to ignore ligatures

- Certain operator combinations - especially those involving equals
 signs - look wrong when some of them form ligatures.

 - All current rules from FiraCode were ported over, but many are
 currently irrelevant for this font. Those are commented out of the
 file.

 - Fixes issue #118

Scripts/features.py

@@ -3,6 +3,7 @@
 # Adapted from https://github.com/tonsky/FiraCode/blob/master/gen_calt.clj
 
 from textwrap import dedent
+from collections import defaultdict
 import tempfile
 
 
@@ -44,7 +45,7 @@ def rule(liga):
                  [LIG   f i] LIG
                  [ f    f i] LIG }
     """
-    # ignores:
+    # standard ignores:
     #   ignore sub {0} {0}' {1};
     #   ignore sub {0}' {1} {1};
     rules = [
@@ -52,6 +53,9 @@ def rule(liga):
         ignore(head=liga[0], suffix=(liga[1:] + [liga[-1]])),
     ]
 
+    # hardcoded ignores, i.e. `<||>`
+    rules.extend(ignores[tuple(liga)])
+
     name = "_".join(liga)
     # substitution logic
     #   sub {0}'  {1}  by LIG;
@@ -81,5 +85,112 @@ def ignore(prefix=None, head=None, suffix=None):
     return "ignore sub{0} {1}'{2};".format(pref, head, rest)
 
 
+ignores = defaultdict(
+    list,
+    {
+        ("slash", "asterisk"): [
+            "ignore sub slash' asterisk slash;",
+            "ignore sub asterisk slash' asterisk;",
+        ],
+        ("asterisk", "slash"): [
+            "ignore sub slash asterisk' slash;",
+            "ignore sub asterisk' slash asterisk;",
+        ],
+        # ("asterisk", "asterisk"): [
+        #     "ignore sub slash asterisk' asterisk;",
+        #     "ignore sub asterisk' asterisk slash;",
+        # ],
+        # ("asterisk", "asterisk", "asterisk"): [
+        #     "ignore sub slash asterisk' asterisk asterisk;",
+        #     "ignore sub asterisk' asterisk asterisk slash;",
+        # ],
+        # <||>
+        ("less", "bar", "bar"): ["ignore sub less' bar bar greater;"],
+        ("bar", "bar", "greater"): ["ignore sub less bar' bar greater;"],
+        # # :>=
+        # ("colon", "greater"): ["ignore sub colon' greater equal;"],
+        # # {|}
+        # ("braceleft", "bar"): ["ignore sub braceleft' bar braceright;"],
+        # ("bar", "braceright"): ["ignore sub braceleft bar' braceright;"],
+        # # [|]
+        # ("bracketleft", "bar"): ["ignore sub bracketleft' bar bracketright;"],
+        # ("bar", "bracketright"): ["ignore sub bracketleft bar' bracketright;"],
+        # # <*>>> <+>>> <$>>>
+        # ("greater", "greater", "greater"): [
+        #     "ignore sub [asterisk plus dollar] greater' greater greater;"
+        # ],
+        # # <<<*> <<<+> <<<$>
+        # ("less", "less", "less"): ["ignore sub less' less less [asterisk plus dollar];"],
+        # # =:=
+        # ("colon", "equal"): ["ignore sub equal colon' equal;"],
+        # =!=
+        ("exclam", "equal"): ["ignore sub equal exclam' equal;"],
+        # =!==
+        ("exclam", "equal", "equal"): ["ignore sub equal exclam' equal equal;"],
+        # =<= <=< <=> <=| <=: <=! <=/
+        ("less", "equal"): [
+            "ignore sub equal less' equal;",
+            "ignore sub less' equal [less greater bar colon exclam slash];",
+        ],
+        # >=<
+        # =>= >=> >=< >=| >=: >=! >=/
+        ("greater", "equal"): [
+            "ignore sub equal greater' equal;",
+            "ignore sub greater' equal [less greater bar colon exclam slash];",
+        ],
+        # <*>> <+>> <$>>
+        # >>->> >>=>>
+        ("greater", "greater"): [
+            # "ignore sub [asterisk plus dollar] greater' greater;",
+            # "ignore sub [hyphen equal] greater' greater;",
+            # "ignore sub greater' greater [hyphen equal];",
+        ],
+        # <<*> <<+> <<$>
+        # <<-<< <<=<<
+        ("less", "less"): [
+            # "ignore sub less' less [asterisk plus dollar];",
+            # "ignore sub [hyphen equal] less' less;",
+            # "ignore sub less' less [hyphen equal];",
+        ],
+        # ||-|| ||=||
+        ("bar", "bar"): [
+            "ignore sub [hyphen equal] bar' bar;",
+            "ignore sub bar' bar [hyphen equal];",
+        ],
+        # # <--> >--< |--|
+        # ("hyphen", "hyphen"): [
+        #     "ignore sub [less greater bar] hyphen' hyphen;",
+        #     "ignore sub hyphen' hyphen [less greater bar];",
+        # ],
+        # # <---> >---< |---|
+        # ("hyphen", "hyphen", "hyphen"):
+        #     "ignore sub [less greater bar] hyphen' hyphen hyphen;",
+        #     "ignore sub hyphen' hyphen hyphen [less greater bar];",
+        # ],
+        ("equal", "equal"): [  # ==
+            # "ignore sub bracketleft equal' equal;", # [==
+            # "ignore sub equal' equal bracketright;",#  ==]
+            "ignore sub equal [colon exclam] equal' equal;",  # =:== =!==
+            # "ignore sub [less greater bar slash] equal' equal;", # <== >== |== /==
+            # "ignore sub equal' equal [less greater bar slash];", # ==< ==> ==| ==/
+            "ignore sub equal' equal [colon exclam] equal;",  # ==:= ==!=
+        ],
+        # [===[ ]===]
+        # [=== ===]
+        # <===> >===< |===| /===/ =:=== =!=== ===:= ===!=
+        ("equal", "equal", "equal"): [
+            # "ignore sub bracketleft equal' equal equal;",
+            # "ignore sub equal' equal equal bracketright;",
+            "ignore sub equal [colon exclam] equal' equal equal;",
+            "ignore sub [less greater bar slash] equal' equal equal;",
+            # "ignore sub equal' equal equal [less greater bar slash];",
+            "ignore sub equal' equal equal [colon exclam] equal;",
+        ],
+        # #118 https://
+        ("slash", "slash"): ["ignore sub colon slash' slash;"],
+    },
+)
+
+
 def indent(text, prefix):
     return '\n'.join(prefix + line for line in text.split('\n'))