Revert "Merge pull request #677 from djc/optimize-tables"

This reverts commit f0010be, reversing
changes made to 74fd76f.

PR was merged without its dependencies.

Author: valenting

idna/src/make_uts46_mapping_table.py

@@ -148,22 +148,30 @@ def merge_single_char_ranges(ranges):
 
 optimized_ranges = list(merge_single_char_ranges(optimized_ranges))
 
-SINGLE_MARKER = 1 << 15
 
-print("static TABLE: &[(char, u16)] = &[")
+print("static TABLE: &[Range] = &[")
+
+for ranges in optimized_ranges:
+    first = ranges[0][0]
+    last = ranges[-1][1]
+    print("    Range { from: '%s', to: '%s', }," % (escape_char(char(first)),
+                                                            escape_char(char(last))))
+
+print("];\n")
+
+print("static INDEX_TABLE: &[u16] = &[")
+
+SINGLE_MARKER = 1 << 15
 
 offset = 0
 for ranges in optimized_ranges:
     assert offset < SINGLE_MARKER
 
     block_len = len(ranges)
     single = SINGLE_MARKER if block_len == 1 else 0
-    index = offset | single
+    print("    %s," % (offset | single))
     offset += block_len
 
-    start = escape_char(char(ranges[0][0]))
-    print("    ('%s', %s)," % (start, index))
-
 print("];\n")
 
 print("static MAPPING_TABLE: &[Mapping] = &[")

idna/src/uts46.rs

@@ -11,6 +11,7 @@
 
 use self::Mapping::*;
 use crate::punycode;
+use std::cmp::Ordering::{Equal, Greater, Less};
 use std::{error::Error as StdError, fmt};
 use unicode_bidi::{bidi_class, BidiClass};
 use unicode_normalization::char::is_combining_mark;
@@ -49,23 +50,36 @@ enum Mapping {
     DisallowedStd3Mapped(StringTableSlice),
 }
 
-fn find_char(codepoint: char) -> &'static Mapping {
-    let idx = match TABLE.binary_search_by_key(&codepoint, |&val| val.0) {
-        Ok(idx) => idx,
-        Err(idx) => idx - 1,
-    };
+struct Range {
+    from: char,
+    to: char,
+}
 
-    const SINGLE_MARKER: u16 = 1 << 15;
+fn find_char(codepoint: char) -> &'static Mapping {
+    let r = TABLE.binary_search_by(|ref range| {
+        if codepoint > range.to {
+            Less
+        } else if codepoint < range.from {
+            Greater
+        } else {
+            Equal
+        }
+    });
+    r.ok()
+        .map(|i| {
+            const SINGLE_MARKER: u16 = 1 << 15;
 
-    let (base, x) = TABLE[idx];
-    let single = (x & SINGLE_MARKER) != 0;
-    let offset = !SINGLE_MARKER & x;
+            let x = INDEX_TABLE[i];
+            let single = (x & SINGLE_MARKER) != 0;
+            let offset = !SINGLE_MARKER & x;
 
-    if single {
-        &MAPPING_TABLE[offset as usize]
-    } else {
-        &MAPPING_TABLE[(offset + (codepoint as u16 - base as u16)) as usize]
-    }
+            if single {
+                &MAPPING_TABLE[offset as usize]
+            } else {
+                &MAPPING_TABLE[(offset + (codepoint as u16 - TABLE[i].from as u16)) as usize]
+            }
+        })
+        .unwrap()
 }
 
 struct Mapper<'a> {