rust/src/etc/unicode.py

#!/usr/bin/env python
#
# Copyright 2011-2013 The Rust Project Developers. See the COPYRIGHT
# file at the top-level directory of this distribution and at
# http://rust-lang.org/COPYRIGHT.
#
# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
# option. This file may not be copied, modified, or distributed
# except according to those terms.

# This script uses the following Unicode tables:
# - DerivedCoreProperties.txt
# - EastAsianWidth.txt
# - PropList.txt
# - Scripts.txt
# - UnicodeData.txt
#
# Since this should not require frequent updates, we just store this
# out-of-line and check the unicode.rs file into git.

import fileinput, re, os, sys, operator

preamble = '''// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// NOTE: The following code was generated by "src/etc/unicode.py", do not edit directly

#![allow(missing_doc, non_uppercase_statics, non_snake_case)]
'''

# Mapping taken from Table 12 from:
# http://www.unicode.org/reports/tr44/#General_Category_Values
expanded_categories = {
    'Lu': ['LC', 'L'], 'Ll': ['LC', 'L'], 'Lt': ['LC', 'L'],
    'Lm': ['L'], 'Lo': ['L'],
    'Mn': ['M'], 'Mc': ['M'], 'Me': ['M'],
    'Nd': ['N'], 'Nl': ['N'], 'No': ['No'],
    'Pc': ['P'], 'Pd': ['P'], 'Ps': ['P'], 'Pe': ['P'],
    'Pi': ['P'], 'Pf': ['P'], 'Po': ['P'],
    'Sm': ['S'], 'Sc': ['S'], 'Sk': ['S'], 'So': ['S'],
    'Zs': ['Z'], 'Zl': ['Z'], 'Zp': ['Z'],
    'Cc': ['C'], 'Cf': ['C'], 'Cs': ['C'], 'Co': ['C'], 'Cn': ['C'],
}


# Grapheme cluster data
# taken from UAX29, http://www.unicode.org/reports/tr29/
# these code points are excluded from the Control category
# NOTE: CR and LF are also technically excluded, but for
# the sake of convenience we leave them in the Control group
# and manually check them in the appropriate place. This is
# still compliant with the implementation requirements.
grapheme_control_exceptions = set([0x200c, 0x200d])

# the Regional_Indicator category
grapheme_regional_indicator = [(0x1f1e6, 0x1f1ff)]

# "The following ... are specifically excluded" from the SpacingMark category
# http://www.unicode.org/reports/tr29/#SpacingMark
grapheme_spacingmark_exceptions = [(0x102b, 0x102c), (0x1038, 0x1038),
    (0x1062, 0x1064), (0x1067, 0x106d), (0x1083, 0x1083), (0x1087, 0x108c),
    (0x108f, 0x108f), (0x109a, 0x109c), (0x19b0, 0x19b4), (0x19b8, 0x19b9),
    (0x19bb, 0x19c0), (0x19c8, 0x19c9), (0x1a61, 0x1a61), (0x1a63, 0x1a64),
    (0xaa7b, 0xaa7b), (0xaa7d, 0xaa7d)]

# these are included in the SpacingMark category
grapheme_spacingmark_extra = set([0xe33, 0xeb3])

def fetch(f):
    if not os.path.exists(f):
        os.system("curl -O http://www.unicode.org/Public/UNIDATA/%s"
                  % f)

    if not os.path.exists(f):
        sys.stderr.write("cannot load %s" % f)
        exit(1)

def is_valid_unicode(n):
    return 0 <= n <= 0xD7FF or 0xE000 <= n <= 0x10FFFF

def load_unicode_data(f):
    fetch(f)
    gencats = {}
    upperlower = {}
    lowerupper = {}
    combines = {}
    canon_decomp = {}
    compat_decomp = {}

    for line in fileinput.input(f):
        fields = line.split(";")
        if len(fields) != 15:
            continue
        [code, name, gencat, combine, bidi,
         decomp, deci, digit, num, mirror,
         old, iso, upcase, lowcase, titlecase ] = fields

        code_org = code
        code     = int(code, 16)

        if not is_valid_unicode(code):
            continue

        # generate char to char direct common and simple conversions
        # uppercase to lowercase
        if gencat == "Lu" and lowcase != "" and code_org != lowcase:
            upperlower[code] = int(lowcase, 16)

        # lowercase to uppercase
        if gencat == "Ll" and upcase != "" and code_org != upcase:
            lowerupper[code] = int(upcase, 16)

        # store decomposition, if given
        if decomp != "":
            if decomp.startswith('<'):
                seq = []
                for i in decomp.split()[1:]:
                    seq.append(int(i, 16))
                compat_decomp[code] = seq
            else:
                seq = []
                for i in decomp.split():
                    seq.append(int(i, 16))
                canon_decomp[code] = seq

        # place letter in categories as appropriate
        for cat in [gencat, "Assigned"] + expanded_categories.get(gencat, []):
            if cat not in gencats:
                gencats[cat] = []
            gencats[cat].append(code)

        # record combining class, if any
        if combine != "0":
            if combine not in combines:
                combines[combine] = []
            combines[combine].append(code)

    # generate Not_Assigned from Assigned
    gencats["Cn"] = gen_unassigned(gencats["Assigned"])
    # Assigned is not a real category
    del(gencats["Assigned"])
    # Other contains Not_Assigned
    gencats["C"].extend(gencats["Cn"])
    gencats = group_cats(gencats)
    combines = to_combines(group_cats(combines))

    return (canon_decomp, compat_decomp, gencats, combines, lowerupper, upperlower)

def group_cats(cats):
    cats_out = {}
    for cat in cats:
        cats_out[cat] = group_cat(cats[cat])
    return cats_out

def group_cat(cat):
    cat_out = []
    letters = sorted(set(cat))
    cur_start = letters.pop(0)
    cur_end = cur_start
    for letter in letters:
        assert letter > cur_end, \
            "cur_end: %s, letter: %s" % (hex(cur_end), hex(letter))
        if letter == cur_end + 1:
            cur_end = letter
        else:
            cat_out.append((cur_start, cur_end))
            cur_start = cur_end = letter
    cat_out.append((cur_start, cur_end))
    return cat_out

def ungroup_cat(cat):
    cat_out = []
    for (lo, hi) in cat:
        while lo <= hi:
            cat_out.append(lo)
            lo += 1
    return cat_out

def gen_unassigned(assigned):
    assigned = set(assigned)
    return ([i for i in range(0, 0xd800) if i not in assigned] +
            [i for i in range(0xe000, 0x110000) if i not in assigned])

def to_combines(combs):
    combs_out = []
    for comb in combs:
        for (lo, hi) in combs[comb]:
            combs_out.append((lo, hi, comb))
    combs_out.sort(key=lambda comb: comb[0])
    return combs_out

def format_table_content(f, content, indent):
    line = " "*indent
    first = True
    for chunk in content.split(","):
        if len(line) + len(chunk) < 98:
            if first:
                line += chunk
            else:
                line += ", " + chunk
            first = False
        else:
            f.write(line + ",\n")
            line = " "*indent + chunk
    f.write(line)

def load_properties(f, interestingprops):
    fetch(f)
    props = {}
    re1 = re.compile("^([0-9A-F]+) +; (\w+)")
    re2 = re.compile("^([0-9A-F]+)\.\.([0-9A-F]+) +; (\w+)")

    for line in fileinput.input(f):
        prop = None
        d_lo = 0
        d_hi = 0
        m = re1.match(line)
        if m:
            d_lo = m.group(1)
            d_hi = m.group(1)
            prop = m.group(2)
        else:
            m = re2.match(line)
            if m:
                d_lo = m.group(1)
                d_hi = m.group(2)
                prop = m.group(3)
            else:
                continue
        if interestingprops and prop not in interestingprops:
            continue
        d_lo = int(d_lo, 16)
        d_hi = int(d_hi, 16)
        if prop not in props:
            props[prop] = []
        props[prop].append((d_lo, d_hi))
    return props

# load all widths of want_widths, except those in except_cats
def load_east_asian_width(want_widths, except_cats):
    f = "EastAsianWidth.txt"
    fetch(f)
    widths = {}
    re1 = re.compile("^([0-9A-F]+);(\w+) +# (\w+)")
    re2 = re.compile("^([0-9A-F]+)\.\.([0-9A-F]+);(\w+) +# (\w+)")

    for line in fileinput.input(f):
        width = None
        d_lo = 0
        d_hi = 0
        cat = None
        m = re1.match(line)
        if m:
            d_lo = m.group(1)
            d_hi = m.group(1)
            width = m.group(2)
            cat = m.group(3)
        else:
            m = re2.match(line)
            if m:
                d_lo = m.group(1)
                d_hi = m.group(2)
                width = m.group(3)
                cat = m.group(4)
            else:
                continue
        if cat in except_cats or width not in want_widths:
            continue
        d_lo = int(d_lo, 16)
        d_hi = int(d_hi, 16)
        if width not in widths:
            widths[width] = []
        widths[width].append((d_lo, d_hi))
    return widths

def escape_char(c):
    if c <= 0xff:
        return "'\\x%2.2x'" % c
    if c <= 0xffff:
        return "'\\u%4.4x'" % c
    return "'\\U%8.8x'" % c

def emit_bsearch_range_table(f):
    f.write("""
fn bsearch_range_table(c: char, r: &'static [(char,char)]) -> bool {
    use core::cmp::{Equal, Less, Greater};
    use core::slice::ImmutableSlice;
    r.binary_search(|&(lo,hi)| {
        if lo <= c && c <= hi { Equal }
        else if hi < c { Less }
        else { Greater }
    }).found().is_some()
}\n
""")

def emit_table(f, name, t_data, t_type = "&'static [(char, char)]", is_pub=True,
        pfun=lambda x: "(%s,%s)" % (escape_char(x[0]), escape_char(x[1]))):
    pub_string = ""
    if is_pub:
        pub_string = "pub "
    f.write("    %sstatic %s: %s = &[\n" % (pub_string, name, t_type))
    data = ""
    first = True
    for dat in t_data:
        if not first:
            data += ","
        first = False
        data += pfun(dat)
    format_table_content(f, data, 8)
    f.write("\n    ];\n\n")

def emit_property_module(f, mod, tbl, emit_fn):
    f.write("pub mod %s {\n" % mod)
    keys = tbl.keys()
    keys.sort()
    for cat in keys:
        emit_table(f, "%s_table" % cat, tbl[cat])
        if cat in emit_fn:
            f.write("    pub fn %s(c: char) -> bool {\n" % cat)
            f.write("        super::bsearch_range_table(c, %s_table)\n" % cat)
            f.write("    }\n\n")
    f.write("}\n\n")

def emit_regex_module(f, cats, w_data):
    f.write("pub mod regex {\n")
    regex_class = "&'static [(char, char)]"
    class_table = "&'static [(&'static str, %s)]" % regex_class

    emit_table(f, "UNICODE_CLASSES", cats, class_table,
        pfun=lambda x: "(\"%s\",super::%s::%s_table)" % (x[0], x[1], x[0]))

    f.write("    pub static PERLD: %s = super::general_category::Nd_table;\n\n"
            % regex_class)
    f.write("    pub static PERLS: %s = super::property::White_Space_table;\n\n"
            % regex_class)

    emit_table(f, "PERLW", w_data, regex_class)

    f.write("}\n\n")

def emit_conversions_module(f, lowerupper, upperlower):
    f.write("pub mod conversions {")
    f.write("""
    use core::cmp::{Equal, Less, Greater};
    use core::slice::ImmutableSlice;
    use core::tuple::Tuple2;
    use core::option::{Option, Some, None};
    use core::slice;

    pub fn to_lower(c: char) -> char {
        match bsearch_case_table(c, LuLl_table) {
          None        => c,
          Some(index) => LuLl_table[index].val1()
        }
    }

    pub fn to_upper(c: char) -> char {
        match bsearch_case_table(c, LlLu_table) {
            None        => c,
            Some(index) => LlLu_table[index].val1()
        }
    }

    fn bsearch_case_table(c: char, table: &'static [(char, char)]) -> Option<uint> {
        match table.binary_search(|&(key, _)| {
            if c == key { Equal }
            else if key < c { Less }
            else { Greater }
        }) {
            slice::Found(i) => Some(i),
            slice::NotFound(_) => None,
        }
    }

""")
    emit_table(f, "LuLl_table",
        sorted(upperlower.iteritems(), key=operator.itemgetter(0)), is_pub=False)
    emit_table(f, "LlLu_table",
        sorted(lowerupper.iteritems(), key=operator.itemgetter(0)), is_pub=False)
    f.write("}\n\n")

def emit_grapheme_module(f, grapheme_table, grapheme_cats):
    f.write("""pub mod grapheme {
    use core::slice::ImmutableSlice;
    use core::slice;

    #[allow(non_camel_case_types)]
    #[deriving(Clone)]
    pub enum GraphemeCat {
""")
    for cat in grapheme_cats + ["Any"]:
        f.write("        GC_" + cat + ",\n")
    f.write("""    }

    fn bsearch_range_value_table(c: char, r: &'static [(char, char, GraphemeCat)]) -> GraphemeCat {
        use core::cmp::{Equal, Less, Greater};
        match r.binary_search(|&(lo, hi, _)| {
            if lo <= c && c <= hi { Equal }
            else if hi < c { Less }
            else { Greater }
        }) {
            slice::Found(idx) => {
                let (_, _, cat) = r[idx];
                cat
            }
            slice::NotFound(_) => GC_Any
        }
    }

    pub fn grapheme_category(c: char) -> GraphemeCat {
        bsearch_range_value_table(c, grapheme_cat_table)
    }

""")

    emit_table(f, "grapheme_cat_table", grapheme_table, "&'static [(char, char, GraphemeCat)]",
        pfun=lambda x: "(%s,%s,GC_%s)" % (escape_char(x[0]), escape_char(x[1]), x[2]),
        is_pub=False)
    f.write("}\n")

def emit_charwidth_module(f, width_table):
    f.write("pub mod charwidth {\n")
    f.write("    use core::option::{Option, Some, None};\n")
    f.write("    use core::slice::ImmutableSlice;\n")
    f.write("    use core::slice;\n")
    f.write("""
    fn bsearch_range_value_table(c: char, is_cjk: bool, r: &'static [(char, char, u8, u8)]) -> u8 {
        use core::cmp::{Equal, Less, Greater};
        match r.binary_search(|&(lo, hi, _, _)| {
            if lo <= c && c <= hi { Equal }
            else if hi < c { Less }
            else { Greater }
        }) {
            slice::Found(idx) => {
                let (_, _, r_ncjk, r_cjk) = r[idx];
                if is_cjk { r_cjk } else { r_ncjk }
            }
            slice::NotFound(_) => 1
        }
    }
""")

    f.write("""
    pub fn width(c: char, is_cjk: bool) -> Option<uint> {
        match c as uint {
            _c @ 0 => Some(0),          // null is zero width
            cu if cu < 0x20 => None,    // control sequences have no width
            cu if cu < 0x7F => Some(1), // ASCII
            cu if cu < 0xA0 => None,    // more control sequences
            _ => Some(bsearch_range_value_table(c, is_cjk, charwidth_table) as uint)
        }
    }

""")

    f.write("    // character width table. Based on Markus Kuhn's free wcwidth() implementation,\n")
    f.write("    //     http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c\n")
    emit_table(f, "charwidth_table", width_table, "&'static [(char, char, u8, u8)]", is_pub=False,
            pfun=lambda x: "(%s,%s,%s,%s)" % (escape_char(x[0]), escape_char(x[1]), x[2], x[3]))
    f.write("}\n\n")

def emit_norm_module(f, canon, compat, combine, norm_props):
    canon_keys = canon.keys()
    canon_keys.sort()

    compat_keys = compat.keys()
    compat_keys.sort()

    canon_comp = {}
    comp_exclusions = norm_props["Full_Composition_Exclusion"]
    for char in canon_keys:
        if True in map(lambda (lo, hi): lo <= char <= hi, comp_exclusions):
            continue
        decomp = canon[char]
        if len(decomp) == 2:
            if not canon_comp.has_key(decomp[0]):
                canon_comp[decomp[0]] = []
            canon_comp[decomp[0]].append( (decomp[1], char) )
    canon_comp_keys = canon_comp.keys()
    canon_comp_keys.sort()

    f.write("pub mod normalization {\n")

    def mkdata_fun(table):
        def f(char):
            data = "(%s,&[" % escape_char(char)
            first = True
            for d in table[char]:
                if not first:
                    data += ","
                first = False
                data += escape_char(d)
            data += "])"
            return data
        return f

    f.write("    // Canonical decompositions\n")
    emit_table(f, "canonical_table", canon_keys, "&'static [(char, &'static [char])]",
        pfun=mkdata_fun(canon))

    f.write("    // Compatibility decompositions\n")
    emit_table(f, "compatibility_table", compat_keys, "&'static [(char, &'static [char])]",
        pfun=mkdata_fun(compat))

    def comp_pfun(char):
        data = "(%s,&[" % escape_char(char)
        canon_comp[char].sort(lambda x, y: x[0] - y[0])
        first = True
        for pair in canon_comp[char]:
            if not first:
                data += ","
            first = False
            data += "(%s,%s)" % (escape_char(pair[0]), escape_char(pair[1]))
        data += "])"
        return data

    f.write("    // Canonical compositions\n")
    emit_table(f, "composition_table", canon_comp_keys,
        "&'static [(char, &'static [(char, char)])]", pfun=comp_pfun)

    f.write("""
    fn bsearch_range_value_table(c: char, r: &'static [(char, char, u8)]) -> u8 {
        use core::cmp::{Equal, Less, Greater};
        use core::slice::ImmutableSlice;
        use core::slice;
        match r.binary_search(|&(lo, hi, _)| {
            if lo <= c && c <= hi { Equal }
            else if hi < c { Less }
            else { Greater }
        }) {
            slice::Found(idx) => {
                let (_, _, result) = r[idx];
                result
            }
            slice::NotFound(_) => 0
        }
    }\n
""")

    emit_table(f, "combining_class_table", combine, "&'static [(char, char, u8)]", is_pub=False,
            pfun=lambda x: "(%s,%s,%s)" % (escape_char(x[0]), escape_char(x[1]), x[2]))

    f.write("    pub fn canonical_combining_class(c: char) -> u8 {\n"
        + "        bsearch_range_value_table(c, combining_class_table)\n"
        + "    }\n")

    f.write("""
}

""")

def remove_from_wtable(wtable, val):
    wtable_out = []
    while wtable:
        if wtable[0][1] < val:
            wtable_out.append(wtable.pop(0))
        elif wtable[0][0] > val:
            break
        else:
            (wt_lo, wt_hi, width, width_cjk) = wtable.pop(0)
            if wt_lo == wt_hi == val:
                continue
            elif wt_lo == val:
                wtable_out.append((wt_lo+1, wt_hi, width, width_cjk))
            elif wt_hi == val:
                wtable_out.append((wt_lo, wt_hi-1, width, width_cjk))
            else:
                wtable_out.append((wt_lo, val-1, width, width_cjk))
                wtable_out.append((val+1, wt_hi, width, width_cjk))
    if wtable:
        wtable_out.extend(wtable)
    return wtable_out



def optimize_width_table(wtable):
    wtable_out = []
    w_this = wtable.pop(0)
    while wtable:
        if w_this[1] == wtable[0][0] - 1 and w_this[2:3] == wtable[0][2:3]:
            w_tmp = wtable.pop(0)
            w_this = (w_this[0], w_tmp[1], w_tmp[2], w_tmp[3])
        else:
            wtable_out.append(w_this)
            w_this = wtable.pop(0)
    wtable_out.append(w_this)
    return wtable_out

if __name__ == "__main__":
    r = "tables.rs"
    if os.path.exists(r):
        os.remove(r)
    with open(r, "w") as rf:
        # write the file's preamble
        rf.write(preamble)

        # download and parse all the data
        (canon_decomp, compat_decomp, gencats, combines,
                lowerupper, upperlower) = load_unicode_data("UnicodeData.txt")
        want_derived = ["XID_Start", "XID_Continue", "Alphabetic", "Lowercase", "Uppercase"]
        other_derived = ["Default_Ignorable_Code_Point", "Grapheme_Extend"]
        derived = load_properties("DerivedCoreProperties.txt", want_derived + other_derived)
        scripts = load_properties("Scripts.txt", [])
        props = load_properties("PropList.txt",
                ["White_Space", "Join_Control", "Noncharacter_Code_Point"])
        norm_props = load_properties("DerivedNormalizationProps.txt",
                     ["Full_Composition_Exclusion"])

        # grapheme cluster category from DerivedCoreProperties
        # the rest are defined below
        grapheme_cats = {}
        grapheme_cats["Extend"] = derived["Grapheme_Extend"]
        del(derived["Grapheme_Extend"])

        # bsearch_range_table is used in all the property modules below
        emit_bsearch_range_table(rf)

        # all of these categories will also be available as \p{} in libregex
        allcats = []
        for (name, cat, pfuns) in ("general_category", gencats, ["N", "Cc"]), \
                                  ("derived_property", derived, want_derived), \
                                  ("script", scripts, []), \
                                  ("property", props, ["White_Space"]):
            emit_property_module(rf, name, cat, pfuns)
            allcats.extend(map(lambda x: (x, name), cat))
        allcats.sort(key=lambda c: c[0])

        # the \w regex corresponds to Alphabetic + Mark + Decimal_Number +
        # Connector_Punctuation + Join-Control according to UTS#18
        # http://www.unicode.org/reports/tr18/#Compatibility_Properties
        perl_words = []
        for cat in derived["Alphabetic"], gencats["M"], gencats["Nd"], \
                   gencats["Pc"], props["Join_Control"]:
            perl_words.extend(ungroup_cat(cat))
        perl_words = group_cat(perl_words)

        # emit lookup tables for \p{}, along with \d, \w, and \s for libregex
        emit_regex_module(rf, allcats, perl_words)

        # normalizations and conversions module
        emit_norm_module(rf, canon_decomp, compat_decomp, combines, norm_props)
        emit_conversions_module(rf, lowerupper, upperlower)

        ### character width module
        width_table = []
        for zwcat in ["Me", "Mn", "Cf"]:
            width_table.extend(map(lambda (lo, hi): (lo, hi, 0, 0), gencats[zwcat]))
        width_table.append((4448, 4607, 0, 0))

        # get widths, except those that are explicitly marked zero-width above
        ea_widths = load_east_asian_width(["W", "F", "A"], ["Me", "Mn", "Cf"])
        # these are doublewidth
        for dwcat in ["W", "F"]:
            width_table.extend(map(lambda (lo, hi): (lo, hi, 2, 2), ea_widths[dwcat]))
        width_table.extend(map(lambda (lo, hi): (lo, hi, 1, 2), ea_widths["A"]))

        width_table.sort(key=lambda w: w[0])

        # soft hyphen is not zero width in preformatted text; it's used to indicate
        # a hyphen inserted to facilitate a linebreak.
        width_table = remove_from_wtable(width_table, 173)

        # optimize the width table by collapsing adjacent entities when possible
        width_table = optimize_width_table(width_table)
        emit_charwidth_module(rf, width_table)

        ### grapheme cluster module
        # from http://www.unicode.org/reports/tr29/#Grapheme_Cluster_Break_Property_Values
        # Hangul syllable categories
        want_hangul = ["L", "V", "T", "LV", "LVT"]
        grapheme_cats.update(load_properties("HangulSyllableType.txt", want_hangul))

        # Control
        # This category also includes Cs (surrogate codepoints), but Rust's `char`s are
        # Unicode Scalar Values only, and surrogates are thus invalid `char`s.
        grapheme_cats["Control"] = set()
        for cat in ["Zl", "Zp", "Cc", "Cf"]:
            grapheme_cats["Control"] |= set(ungroup_cat(gencats[cat]))
        grapheme_cats["Control"] = group_cat(list(
            grapheme_cats["Control"]
            - grapheme_control_exceptions
            | (set(ungroup_cat(gencats["Cn"]))
               & set(ungroup_cat(derived["Default_Ignorable_Code_Point"])))))

        # Regional Indicator
        grapheme_cats["RegionalIndicator"] = grapheme_regional_indicator

        # Prepend - "Currently there are no characters with this value"
        # (from UAX#29, Unicode 7.0)

        # SpacingMark
        grapheme_cats["SpacingMark"] = group_cat(list(
            set(ungroup_cat(gencats["Mc"]))
            - set(ungroup_cat(grapheme_cats["Extend"]))
            | grapheme_spacingmark_extra
            - set(ungroup_cat(grapheme_spacingmark_exceptions))))

        grapheme_table = []
        for cat in grapheme_cats:
            grapheme_table.extend([(x, y, cat) for (x, y) in grapheme_cats[cat]])
        grapheme_table.sort(key=lambda w: w[0])
        emit_grapheme_module(rf, grapheme_table, grapheme_cats.keys())