1 files changed, 243 insertions, 0 deletions
diff --git a/library/core/src/unicode/printable.py b/library/core/src/unicode/printable.py
new file mode 100755
index 000000000..7c37f5f09
--- /dev/null
+++ b/library/core/src/unicode/printable.py
@@ -0,0 +1,243 @@
+#!/usr/bin/env python
+
+# This script uses the following Unicode tables:
+# - UnicodeData.txt
+
+
+from collections import namedtuple
+import csv
+import os
+import subprocess
+
+NUM_CODEPOINTS=0x110000
+
+def to_ranges(iter):
+    current = None
+    for i in iter:
+        if current is None or i != current[1] or i in (0x10000, 0x20000):
+            if current is not None:
+                yield tuple(current)
+            current = [i, i + 1]
+        else:
+            current[1] += 1
+    if current is not None:
+        yield tuple(current)
+
+def get_escaped(codepoints):
+    for c in codepoints:
+        if (c.class_ or "Cn") in "Cc Cf Cs Co Cn Zl Zp Zs".split() and c.value != ord(' '):
+            yield c.value
+
+def get_file(f):
+    try:
+        return open(os.path.basename(f))
+    except FileNotFoundError:
+        subprocess.run(["curl", "-O", f], check=True)
+        return open(os.path.basename(f))
+
+Codepoint = namedtuple('Codepoint', 'value class_')
+
+def get_codepoints(f):
+    r = csv.reader(f, delimiter=";")
+    prev_codepoint = 0
+    class_first = None
+    for row in r:
+        codepoint = int(row[0], 16)
+        name = row[1]
+        class_ = row[2]
+
+        if class_first is not None:
+            if not name.endswith("Last>"):
+                raise ValueError("Missing Last after First")
+
+        for c in range(prev_codepoint + 1, codepoint):
+            yield Codepoint(c, class_first)
+
+        class_first = None
+        if name.endswith("First>"):
+            class_first = class_
+
+        yield Codepoint(codepoint, class_)
+        prev_codepoint = codepoint
+
+    if class_first is not None:
+        raise ValueError("Missing Last after First")
+
+    for c in range(prev_codepoint + 1, NUM_CODEPOINTS):
+        yield Codepoint(c, None)
+
+def compress_singletons(singletons):
+    uppers = [] # (upper, # items in lowers)
+    lowers = []
+
+    for i in singletons:
+        upper = i >> 8
+        lower = i & 0xff
+        if len(uppers) == 0 or uppers[-1][0] != upper:
+            uppers.append((upper, 1))
+        else:
+            upper, count = uppers[-1]
+            uppers[-1] = upper, count + 1
+        lowers.append(lower)
+
+    return uppers, lowers
+
+def compress_normal(normal):
+    # lengths 0x00..0x7f are encoded as 00, 01, ..., 7e, 7f
+    # lengths 0x80..0x7fff are encoded as 80 80, 80 81, ..., ff fe, ff ff
+    compressed = [] # [truelen, (truelenaux), falselen, (falselenaux)]
+
+    prev_start = 0
+    for start, count in normal:
+        truelen = start - prev_start
+        falselen = count
+        prev_start = start + count
+
+        assert truelen < 0x8000 and falselen < 0x8000
+        entry = []
+        if truelen > 0x7f:
+            entry.append(0x80 | (truelen >> 8))
+            entry.append(truelen & 0xff)
+        else:
+            entry.append(truelen & 0x7f)
+        if falselen > 0x7f:
+            entry.append(0x80 | (falselen >> 8))
+            entry.append(falselen & 0xff)
+        else:
+            entry.append(falselen & 0x7f)
+
+        compressed.append(entry)
+
+    return compressed
+
+def print_singletons(uppers, lowers, uppersname, lowersname):
+    print("#[rustfmt::skip]")
+    print("const {}: &[(u8, u8)] = &[".format(uppersname))
+    for u, c in uppers:
+        print("    ({:#04x}, {}),".format(u, c))
+    print("];")
+    print("#[rustfmt::skip]")
+    print("const {}: &[u8] = &[".format(lowersname))
+    for i in range(0, len(lowers), 8):
+        print("    {}".format(" ".join("{:#04x},".format(l) for l in lowers[i:i+8])))
+    print("];")
+
+def print_normal(normal, normalname):
+    print("#[rustfmt::skip]")
+    print("const {}: &[u8] = &[".format(normalname))
+    for v in normal:
+        print("    {}".format(" ".join("{:#04x},".format(i) for i in v)))
+    print("];")
+
+def main():
+    file = get_file("https://www.unicode.org/Public/UNIDATA/UnicodeData.txt")
+
+    codepoints = get_codepoints(file)
+
+    CUTOFF=0x10000
+    singletons0 = []
+    singletons1 = []
+    normal0 = []
+    normal1 = []
+    extra = []
+
+    for a, b in to_ranges(get_escaped(codepoints)):
+        if a > 2 * CUTOFF:
+            extra.append((a, b - a))
+        elif a == b - 1:
+            if a & CUTOFF:
+                singletons1.append(a & ~CUTOFF)
+            else:
+                singletons0.append(a)
+        elif a == b - 2:
+            if a & CUTOFF:
+                singletons1.append(a & ~CUTOFF)
+                singletons1.append((a + 1) & ~CUTOFF)
+            else:
+                singletons0.append(a)
+                singletons0.append(a + 1)
+        else:
+            if a >= 2 * CUTOFF:
+                extra.append((a, b - a))
+            elif a & CUTOFF:
+                normal1.append((a & ~CUTOFF, b - a))
+            else:
+                normal0.append((a, b - a))
+
+    singletons0u, singletons0l = compress_singletons(singletons0)
+    singletons1u, singletons1l = compress_singletons(singletons1)
+    normal0 = compress_normal(normal0)
+    normal1 = compress_normal(normal1)
+
+    print("""\
+// NOTE: The following code was generated by "library/core/src/unicode/printable.py",
+//       do not edit directly!
+
+fn check(x: u16, singletonuppers: &[(u8, u8)], singletonlowers: &[u8], normal: &[u8]) -> bool {
+    let xupper = (x >> 8) as u8;
+    let mut lowerstart = 0;
+    for &(upper, lowercount) in singletonuppers {
+        let lowerend = lowerstart + lowercount as usize;
+        if xupper == upper {
+            for &lower in &singletonlowers[lowerstart..lowerend] {
+                if lower == x as u8 {
+                    return false;
+                }
+            }
+        } else if xupper < upper {
+            break;
+        }
+        lowerstart = lowerend;
+    }
+
+    let mut x = x as i32;
+    let mut normal = normal.iter().cloned();
+    let mut current = true;
+    while let Some(v) = normal.next() {
+        let len = if v & 0x80 != 0 {
+            ((v & 0x7f) as i32) << 8 | normal.next().unwrap() as i32
+        } else {
+            v as i32
+        };
+        x -= len;
+        if x < 0 {
+            break;
+        }
+        current = !current;
+    }
+    current
+}
+
+pub(crate) fn is_printable(x: char) -> bool {
+    let x = x as u32;
+    let lower = x as u16;
+
+    if x < 32 {
+        // ASCII fast path
+        false
+    } else if x < 127 {
+        // ASCII fast path
+        true
+    } else if x < 0x10000 {
+        check(lower, SINGLETONS0U, SINGLETONS0L, NORMAL0)
+    } else if x < 0x20000 {
+        check(lower, SINGLETONS1U, SINGLETONS1L, NORMAL1)
+    } else {\
+""")
+    for a, b in extra:
+        print("        if 0x{:x} <= x && x < 0x{:x} {{".format(a, a + b))
+        print("            return false;")
+        print("        }")
+    print("""\
+        true
+    }
+}\
+""")
+    print()
+    print_singletons(singletons0u, singletons0l, 'SINGLETONS0U', 'SINGLETONS0L')
+    print_singletons(singletons1u, singletons1l, 'SINGLETONS1U', 'SINGLETONS1L')
+    print_normal(normal0, 'NORMAL0')
+    print_normal(normal1, 'NORMAL1')
+
+if __name__ == '__main__':
+    main()