Implement lower, upper case conversion for char

Author: Piotr Zolnierek

src/etc/unicode.py

@@ -19,7 +19,7 @@
 # programs". It is not meant to be a complete implementation of unicode.
 # For that we recommend you use a proper binding to libicu.
 
-import fileinput, re, os, sys
+import fileinput, re, os, sys, operator
 
 
 def fetch(f):
@@ -35,6 +35,8 @@ def fetch(f):
 def load_unicode_data(f):
     fetch(f)
     gencats = {}
+    upperlower = {}
+    lowerupper = {}
     combines = []
     canon_decomp = {}
     compat_decomp = {}
@@ -44,6 +46,7 @@ def load_unicode_data(f):
     c_hi = 0
     com_lo = 0
     com_hi = 0
+
     for line in fileinput.input(f):
         fields = line.split(";")
         if len(fields) != 15:
@@ -52,7 +55,17 @@ def load_unicode_data(f):
          decomp, deci, digit, num, mirror,
          old, iso, upcase, lowcase, titlecase ] = fields
 
-        code = int(code, 16)
+        code_org = code
+        code     = int(code, 16)
+
+        # 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)
 
         if decomp != "":
             if decomp.startswith('<'):
@@ -96,7 +109,7 @@ def load_unicode_data(f):
             com_lo = code
             com_hi = code
 
-    return (canon_decomp, compat_decomp, gencats, combines)
+    return (canon_decomp, compat_decomp, gencats, combines, lowerupper, upperlower)
 
 def load_properties(f, interestingprops):
     fetch(f)
@@ -164,11 +177,12 @@ def emit_property_module(f, mod, tbl):
     keys = tbl.keys()
     keys.sort()
     emit_bsearch_range_table(f);
+
     for cat in keys:
         if cat not in ["Nd", "Nl", "No", "Cc",
-                "XID_Start", "XID_Continue", "Alphabetic",
-                "Lowercase", "Uppercase", "White_Space"]:
-                continue
+            "XID_Start", "XID_Continue", "Alphabetic",
+            "Lowercase", "Uppercase", "White_Space"]:
+            continue
         f.write("    static %s_table : &'static [(char,char)] = &[\n" % cat)
         ix = 0
         for pair in tbl[cat]:
@@ -183,30 +197,58 @@ def emit_property_module(f, mod, tbl):
     f.write("}\n")
 
 
-def emit_property_module_old(f, mod, tbl):
-    f.write("mod %s {\n" % mod)
-    keys = tbl.keys()
-    keys.sort()
-    for cat in keys:
-        f.write("    fn %s(c: char) -> bool {\n" % cat)
-        f.write("        ret alt c {\n")
-        prefix = ' '
-        for pair in tbl[cat]:
-            if pair[0] == pair[1]:
-                f.write("            %c %s\n" %
-                        (prefix, escape_char(pair[0])))
-            else:
-                f.write("            %c %s to %s\n" %
-                        (prefix,
-                         escape_char(pair[0]),
-                         escape_char(pair[1])))
-            prefix = '|'
-        f.write("              { true }\n")
-        f.write("            _ { false }\n")
-        f.write("        };\n")
-        f.write("    }\n\n")
+def emit_conversions_module(f, lowerupper, upperlower):
+    f.write("pub mod conversions {\n")
+    f.write("""
+    use cmp::{Equal, Less, Greater};
+    use vec::ImmutableVector;
+    use tuple::Tuple2;
+    use option::{ Option, Some, None };
+
+    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> {
+        table.bsearch(|&(key, _)| {
+            if c == key { Equal }
+            else if key < c { Less }
+            else { Greater }
+        })
+    }
+""");
+    emit_caseconversions(f, lowerupper, upperlower)
     f.write("}\n")
 
+def emit_caseconversions(f, lowerupper, upperlower):
+    f.write("   static LuLl_table : &'static [(char, char)] = &[\n")
+    sorted_by_lu = sorted(upperlower.iteritems(), key=operator.itemgetter(0))
+    ix = 0
+    for key, value in sorted_by_lu:
+        f.write(ch_prefix(ix))
+        f.write("(%s, %s)" % (escape_char(key), escape_char(value)))
+        ix += 1
+    f.write("\n    ];\n\n")
+
+    f.write("   static LlLu_table : &'static [(char, char)] = &[\n")
+    sorted_by_ll = sorted(lowerupper.iteritems(), key=operator.itemgetter(0))
+    ix = 0
+    for key, value in sorted_by_ll:
+        f.write(ch_prefix(ix))
+        f.write("(%s, %s)" % (escape_char(key), escape_char(value)))
+        ix += 1
+    f.write("\n    ];\n\n")
+
 def format_table_content(f, content, indent):
     line = " "*indent
     first = True
@@ -362,7 +404,8 @@ def emit_decomp_module(f, canon, compat, combine):
         os.remove(i);
 rf = open(r, "w")
 
-(canon_decomp, compat_decomp, gencats, combines) = load_unicode_data("UnicodeData.txt")
+(canon_decomp, compat_decomp, gencats,
+ combines, lowerupper, upperlower) = load_unicode_data("UnicodeData.txt")
 
 # Preamble
 rf.write('''// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
@@ -388,7 +431,9 @@ def emit_decomp_module(f, canon, compat, combine):
 
 derived = load_properties("DerivedCoreProperties.txt",
         ["XID_Start", "XID_Continue", "Alphabetic", "Lowercase", "Uppercase"])
+
 emit_property_module(rf, "derived_property", derived)
 
 props = load_properties("PropList.txt", ["White_Space"])
 emit_property_module(rf, "property", props)
+emit_conversions_module(rf, lowerupper, upperlower)

src/libstd/char.rs

@@ -28,7 +28,7 @@ use cast::transmute;
 use option::{None, Option, Some};
 use iter::{Iterator, range_step};
 use str::StrSlice;
-use unicode::{derived_property, property, general_category, decompose};
+use unicode::{derived_property, property, general_category, decompose, conversions};
 
 #[cfg(test)] use str::OwnedStr;
 
@@ -225,6 +225,32 @@ pub fn to_digit(c: char, radix: uint) -> Option<uint> {
     else { None }
 }
 
+/// Convert a char to its uppercase equivalent
+///
+/// The case-folding performed is the common or simple mapping:
+/// it only maps a codepoint to its equivalent if it is also a single codepoint
+///
+/// # Return value
+///
+/// Returns the char itself if no conversion if possible
+#[inline]
+pub fn to_uppercase(c: char) -> char {
+    conversions::to_upper(c)
+}
+
+/// Convert a char to its lowercase equivalent
+///
+/// The case-folding performed is the common or simple mapping:
+/// it only maps a codepoint to its equivalent if it is also a single codepoint
+///
+/// # Return value
+///
+/// Returns the char itself if no conversion if possible
+#[inline]
+pub fn to_lowercase(c: char) -> char {
+    conversions::to_lower(c)
+}
+
 ///
 /// Converts a number to the character representing it
 ///
@@ -385,6 +411,8 @@ pub trait Char {
     fn is_digit(&self) -> bool;
     fn is_digit_radix(&self, radix: uint) -> bool;
     fn to_digit(&self, radix: uint) -> Option<uint>;
+    fn to_lowercase(&self) -> char;
+    fn to_uppercase(&self) -> char;
     fn from_digit(num: uint, radix: uint) -> Option<char>;
     fn escape_unicode(&self, f: |char|);
     fn escape_default(&self, f: |char|);
@@ -421,6 +449,10 @@ impl Char for char {
 
     fn to_digit(&self, radix: uint) -> Option<uint> { to_digit(*self, radix) }
 
+    fn to_lowercase(&self) -> char { to_lowercase(*self) }
+
+    fn to_uppercase(&self) -> char { to_uppercase(*self) }
+
     fn from_digit(num: uint, radix: uint) -> Option<char> { from_digit(num, radix) }
 
     fn escape_unicode(&self, f: |char|) { escape_unicode(*self, f) }
@@ -516,6 +548,39 @@ fn test_to_digit() {
     assert_eq!('$'.to_digit(36u), None);
 }
 
+#[test]
+fn test_to_lowercase() {
+    assert_eq!('A'.to_lowercase(), 'a');
+    assert_eq!('Ö'.to_lowercase(), 'ö');
+    assert_eq!('ß'.to_lowercase(), 'ß');
+    assert_eq!('Ü'.to_lowercase(), 'ü');
+    assert_eq!('💩'.to_lowercase(), '💩');
+    assert_eq!('Σ'.to_lowercase(), 'σ');
+    assert_eq!('Τ'.to_lowercase(), 'τ');
+    assert_eq!('Ι'.to_lowercase(), 'ι');
+    assert_eq!('Γ'.to_lowercase(), 'γ');
+    assert_eq!('Μ'.to_lowercase(), 'μ');
+    assert_eq!('Α'.to_lowercase(), 'α');
+    assert_eq!('Σ'.to_lowercase(), 'σ');
+}
+
+#[test]
+fn test_to_uppercase() {
+    assert_eq!('a'.to_uppercase(), 'A');
+    assert_eq!('ö'.to_uppercase(), 'Ö');
+    assert_eq!('ß'.to_uppercase(), 'ß'); // not ẞ: Latin capital letter sharp s
+    assert_eq!('ü'.to_uppercase(), 'Ü');
+    assert_eq!('💩'.to_uppercase(), '💩');
+
+    assert_eq!('σ'.to_uppercase(), 'Σ');
+    assert_eq!('τ'.to_uppercase(), 'Τ');
+    assert_eq!('ι'.to_uppercase(), 'Ι');
+    assert_eq!('γ'.to_uppercase(), 'Γ');
+    assert_eq!('μ'.to_uppercase(), 'Μ');
+    assert_eq!('α'.to_uppercase(), 'Α');
+    assert_eq!('ς'.to_uppercase(), 'Σ');
+}
+
 #[test]
 fn test_is_control() {
     assert!('\u0000'.is_control());