240 lines
8.1 KiB
Python
240 lines
8.1 KiB
Python
# Generate features for ligatures
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#
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# Adapted from https://github.com/tonsky/FiraCode/blob/master/gen_calt.clj
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from __future__ import unicode_literals
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from textwrap import dedent
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from collections import defaultdict
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import tempfile
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def update_features(font):
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"""Find ligatures in the font and generate features for them."""
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# [ ["dash" "greater" "greater"] ... ]
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ligas = [name[:-len('.liga')].split('_')
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for name in font if name.endswith('.liga') and
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font[name].isWorthOutputting()]
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rules = '\n\n'.join(rule(liga)
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for liga in sorted(ligas, key=lambda l: -len(l)))
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fea_code = dedent('''\
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languagesystem DFLT dflt;
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languagesystem latn dflt;
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languagesystem grek dflt;
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languagesystem cyrl dflt;
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feature calt {{
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{}
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}} calt;
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''').format(indent(rules, ' '))
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# print(fea_code) # DEBUG
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# Add the dummy "LIG" glyph
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lig = font.createChar(-1, 'LIG')
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lig.width = font['space'].width
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with tempfile.NamedTemporaryFile(mode='w', suffix='.fea') as f:
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f.write(fea_code)
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f.seek(0)
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font.mergeFeature(f.name)
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def rule(liga):
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"""
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[f f i] => { [LIG LIG i] f_f_i.liga
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[LIG f i] LIG
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[ f f i] LIG }
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"""
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rules = []
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# standard ignores:
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# ignore sub {0} {0}' {1};
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# ignore sub {0}' {1} {1};
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if tuple(liga) not in skip_ignores:
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rules.extend(
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[
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ignore(prefix=liga[:1], head=liga[0], suffix=liga[1:]),
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ignore(head=liga[0], suffix=(liga[1:] + [liga[-1]])),
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]
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)
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# careful with repeats:
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# #133 ->->->->, /**/**/**/, etc.
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if len(liga) > 2 and liga[0] == liga[-1]:
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rules.append(ignore([liga[-2]], liga[0], liga[1:]))
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rules.append(ignore(head=liga[0], suffix=(liga[1:] + [liga[1]])))
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# Don't cut into `prefix` to complete a ligature.
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# i.e. regex `(?=`> is not `(?`=>.
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rules.extend(
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[
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ignore(prefix[:-n], liga[0], liga[1:])
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for prefix in ignore_prefixes
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for n in range(1, len(liga))
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if prefix[-n:] == liga[:n]
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]
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)
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# hardcoded ignores, i.e. `<||>`
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rules.extend(ignores[tuple(liga)])
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name = "_".join(liga)
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# substitution logic
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# sub {0}' {1} by LIG;
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# sub LIG {1}' by {0}_{1}.liga;
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for i in range(len(liga)):
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init = _join(["LIG" for lig in liga[:i]])
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tail = _join(liga[i + 1 :])
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replace = "LIG" if (i + 1 < len(liga)) else (name + ".liga")
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rules.append("sub{0} {1}'{2} by {3};".format(init, liga[i], tail, replace))
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# put it all together
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lines = (
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["lookup " + name + " {"] + [" " + r for r in rules] + ["}} {0};".format(name)]
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)
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return "\n".join(lines)
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def _join(items):
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return (" " + " ".join(items)) if items else ""
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def ignore(prefix=None, head=None, suffix=None):
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""" don't substitute `head` if it's surrounded by `prefix` and `suffix` """
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assert head
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pref = _join(prefix)
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rest = _join(suffix)
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return "ignore sub{0} {1}'{2};".format(pref, head, rest)
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ignores = defaultdict(
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list,
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{
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("slash", "asterisk"): [
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"ignore sub slash' asterisk slash;",
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"ignore sub asterisk slash' asterisk;",
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],
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("asterisk", "slash"): [
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"ignore sub slash asterisk' slash;",
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"ignore sub asterisk' slash asterisk;",
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],
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# ("asterisk", "asterisk"): [
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# "ignore sub slash asterisk' asterisk;",
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# "ignore sub asterisk' asterisk slash;",
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# ],
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# ("asterisk", "asterisk", "asterisk"): [
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# "ignore sub slash asterisk' asterisk asterisk;",
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# "ignore sub asterisk' asterisk asterisk slash;",
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# ],
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# <||>
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("less", "bar", "bar"): ["ignore sub less' bar bar greater;"],
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("bar", "bar", "greater"): ["ignore sub less bar' bar greater;"],
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# # :>=
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# ("colon", "greater"): ["ignore sub colon' greater equal;"],
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# # {|}
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# ("braceleft", "bar"): ["ignore sub braceleft' bar braceright;"],
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# ("bar", "braceright"): ["ignore sub braceleft bar' braceright;"],
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# # [|]
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# ("bracketleft", "bar"): ["ignore sub bracketleft' bar bracketright;"],
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# ("bar", "bracketright"): ["ignore sub bracketleft bar' bracketright;"],
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# # <*>>> <+>>> <$>>>
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# ("greater", "greater", "greater"): [
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# "ignore sub [asterisk plus dollar] greater' greater greater;"
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# ],
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# # <<<*> <<<+> <<<$>
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# ("less", "less", "less"): ["ignore sub less' less less [asterisk plus dollar];"],
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# # =:=
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# ("colon", "equal"): ["ignore sub equal colon' equal;"],
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# =!=
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("exclam", "equal"): ["ignore sub equal exclam' equal;"],
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# =!==
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("exclam", "equal", "equal"): ["ignore sub equal exclam' equal equal;"],
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# =<= <=< <=> <=| <=: <=! <=/
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("less", "equal"): [
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"ignore sub equal less' equal;",
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"ignore sub less' equal [less greater bar colon exclam slash];",
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],
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# >=<
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# =>= >=> >=< >=| >=: >=! >=/
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("greater", "equal"): [
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"ignore sub equal greater' equal;",
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"ignore sub greater' equal [less greater bar colon exclam slash];",
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],
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# <*>> <+>> <$>>
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# >>->> >>=>>
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("greater", "greater"): [
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# "ignore sub [asterisk plus dollar] greater' greater;",
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# "ignore sub [hyphen equal] greater' greater;",
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# "ignore sub greater' greater [hyphen equal];",
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],
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# <<*> <<+> <<$>
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# <<-<< <<=<<
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("less", "less"): [
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# "ignore sub less' less [asterisk plus dollar];",
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# "ignore sub [hyphen equal] less' less;",
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# "ignore sub less' less [hyphen equal];",
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],
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# ||-|| ||=||
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("bar", "bar"): [
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"ignore sub [hyphen equal] bar' bar;",
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"ignore sub bar' bar [hyphen equal];",
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],
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# # <--> >--< |--|
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# ("hyphen", "hyphen"): [
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# "ignore sub [less greater bar] hyphen' hyphen;",
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# "ignore sub hyphen' hyphen [less greater bar];",
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# ],
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# # <---> >---< |---|
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# ("hyphen", "hyphen", "hyphen"):
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# "ignore sub [less greater bar] hyphen' hyphen hyphen;",
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# "ignore sub hyphen' hyphen hyphen [less greater bar];",
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# ],
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("equal", "equal"): [ # ==
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# "ignore sub bracketleft equal' equal;", # [==
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# "ignore sub equal' equal bracketright;",# ==]
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"ignore sub equal [colon exclam] equal' equal;", # =:== =!==
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# "ignore sub [less greater bar slash] equal' equal;", # <== >== |== /==
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# "ignore sub equal' equal [less greater bar slash];", # ==< ==> ==| ==/
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"ignore sub equal' equal [colon exclam] equal;", # ==:= ==!=
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],
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# [===[ ]===]
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# [=== ===]
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# <===> >===< |===| /===/ =:=== =!=== ===:= ===!=
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("equal", "equal", "equal"): [
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# "ignore sub bracketleft equal' equal equal;",
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# "ignore sub equal' equal equal bracketright;",
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"ignore sub equal [colon exclam] equal' equal equal;",
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"ignore sub [less greater bar slash] equal' equal equal;",
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# "ignore sub equal' equal equal [less greater bar slash];",
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"ignore sub equal' equal equal [colon exclam] equal;",
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],
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# #118 https://
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("slash", "slash"): ["ignore sub colon slash' slash;"],
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},
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)
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ignore_prefixes = [
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["parenleft", "question", "colon"],
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# Regexp lookahead/lookbehind
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["parenleft", "question", "equal"],
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["parenleft", "question", "less", "equal"],
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["parenleft", "question", "exclam"],
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["parenleft", "question", "less", "exclam"],
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# PHP <?=
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["less", "question", "equal"],
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]
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# DO NOT generate ignores at all
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skip_ignores = {
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# # <<*>> <<+>> <<$>>
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# ("less", "asterisk", "greater"),
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# ("less", "plus", "greater"),
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# ("less", "dollar", "greater"),
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}
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def indent(text, prefix):
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return '\n'.join(prefix + line for line in text.split('\n'))
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