lib/core: Improve speed of an indexed access in a UTF-8 `Text` entity
[nit.git] / lib / core / text / flat.nit
index b2336e6..6e1e610 100644 (file)
@@ -40,7 +40,7 @@ redef class FlatText
        protected fun first_byte: Int do return 0
 
        # Last byte of the NativeString
-       protected fun last_byte: Int do return _bytelen - 1
+       protected fun last_byte: Int do return first_byte + _bytelen - 1
 
        # Cache of the latest position (char) explored in the string
        var position: Int = 0
@@ -50,10 +50,24 @@ redef class FlatText
 
        # Index of the character `index` in `_items`
        fun char_to_byte_index(index: Int): Int do
-               var ln = length
-               assert index >= 0
-               assert index < ln
+               var dpos = index - _position
+               var b = _bytepos
+
+               if dpos == 0 then return b
+               if dpos == 1 then
+                       b += _items.length_of_char_at(b)
+                       _bytepos = b
+                       _position = index
+                       return b
+               end
+               if dpos == -1 then
+                       b = _items.find_beginning_of_char_at(b - 1)
+                       _bytepos = b
+                       _position = index
+                       return b
+               end
 
+               var ln = _length
                var pos = _position
                # Find best insertion point
                var delta_begin = index
@@ -68,15 +82,15 @@ redef class FlatText
                var ns_i: Int
                var my_i: Int
 
-               if min == delta_begin then
-                       ns_i = first_byte
-                       my_i = 0
-               else if min == delta_cache then
+               if min == delta_cache then
                        ns_i = _bytepos
                        my_i = pos
+               else if min == delta_begin then
+                       ns_i = first_byte
+                       my_i = 0
                else
                        ns_i = its.find_beginning_of_char_at(last_byte)
-                       my_i = length - 1
+                       my_i = _length - 1
                end
 
                ns_i = its.char_to_byte_index_cached(index, my_i, ns_i)
@@ -181,7 +195,7 @@ redef class FlatText
                        end
                        pos += 1
                end
-               var s = new FlatString.with_infos(nits, nlen, 0, nlen - 1)
+               var s = new FlatString.with_infos(nits, nlen, 0)
                return s
        end
 
@@ -274,10 +288,24 @@ redef class FlatText
                        end
                        pos += 1
                end
-               return nns.to_s_with_length(nlen)
+               return nns.to_s_unsafe(nlen)
        end
 
-       redef fun [](index) do return _items.char_at(char_to_byte_index(index))
+       redef fun [](index) do
+               assert index >= 0 and index < _length
+               return fetch_char_at(index)
+       end
+
+       # Gets a `Char` at `index` in `self`
+       #
+       # WARNING: Use at your own risks as no bound-checking is done
+       fun fetch_char_at(index: Int): Char do
+               var i = char_to_byte_index(index)
+               var items = _items
+               var b = items[i]
+               if b & 0x80u8 == 0x00u8 then return b.ascii
+               return items.char_at(i)
+       end
 
        # If `self` contains only digits and alpha <= 'f', return the corresponding integer.
        #
@@ -305,18 +333,10 @@ class FlatString
        # Index at which `self` begins in `_items`, inclusively
        redef var first_byte is noinit
 
-       # Index at which `self` ends in `_items`, inclusively
-       redef var last_byte is noinit
-
        redef var chars = new FlatStringCharView(self) is lazy
 
        redef var bytes = new FlatStringByteView(self) is lazy
 
-       redef var length is lazy do
-               if _bytelen == 0 then return 0
-               return _items.utf8_length(_first_byte, _last_byte)
-       end
-
        redef var to_cstring is lazy do
                var blen = _bytelen
                var new_items = new NativeString(blen + 1)
@@ -325,14 +345,15 @@ class FlatString
                return new_items
        end
 
-       redef fun reversed
-       do
+       redef fun reversed do
                var b = new FlatBuffer.with_capacity(_bytelen + 1)
-               for i in [length - 1 .. 0].step(-1) do
-                       b.add self[i]
+               var i = _length - 1
+               while i >= 0 do
+                       b.add self.fetch_char_at(i)
+                       i -= 1
                end
                var s = b.to_s.as(FlatString)
-               s.length = self.length
+               s._length = self._length
                return s
        end
 
@@ -367,7 +388,7 @@ class FlatString
        do
                var outstr = new FlatBuffer.with_capacity(self._bytelen + 1)
 
-               var mylen = length
+               var mylen = _length
                var pos = 0
 
                while pos < mylen do
@@ -382,7 +403,7 @@ class FlatString
        do
                var outstr = new FlatBuffer.with_capacity(self._bytelen + 1)
 
-               var mylen = length
+               var mylen = _length
                var pos = 0
 
                while pos < mylen do
@@ -406,26 +427,25 @@ class FlatString
        #
        # `_items` will be used as is, without copy, to retrieve the characters of the string.
        # Aliasing issues is the responsibility of the caller.
-       private init with_infos(items: NativeString, bytelen, from, to: Int)
+       private init with_infos(items: NativeString, bytelen, from: Int)
        do
                self._items = items
                self._bytelen = bytelen
                _first_byte = from
-               _last_byte = to
                _bytepos = from
+               _length = _items.utf8_length(_first_byte, last_byte)
        end
 
        # Low-level creation of a new string with all the data.
        #
        # `_items` will be used as is, without copy, to retrieve the characters of the string.
        # Aliasing issues is the responsibility of the caller.
-       private init full(items: NativeString, bytelen, from, to, length: Int)
+       private init full(items: NativeString, bytelen, from, length: Int)
        do
                self._items = items
-               self.length = length
+               self._length = length
                self._bytelen = bytelen
                _first_byte = from
-               _last_byte = to
                _bytepos = from
        end
 
@@ -499,7 +519,7 @@ class FlatString
                        var ns = new NativeString(nlen + 1)
                        mits.copy_to(ns, mlen, mifrom, 0)
                        sits.copy_to(ns, slen, sifrom, mlen)
-                       return new FlatString.full(ns, nlen, 0, nlen - 1, length + o.length)
+                       return new FlatString.full(ns, nlen, 0, _length + o.length)
                else
                        abort
                end
@@ -508,7 +528,7 @@ class FlatString
        redef fun *(i) do
                var mybtlen = _bytelen
                var new_bytelen = mybtlen * i
-               var mylen = length
+               var mylen = _length
                var newlen = mylen * i
                var its = _items
                var fb = _first_byte
@@ -520,7 +540,7 @@ class FlatString
                        offset += mybtlen
                        i -= 1
                end
-               return new FlatString.full(ns, new_bytelen, 0, new_bytelen - 1, newlen)
+               return new FlatString.full(ns, new_bytelen, 0, newlen)
        end
 
 
@@ -532,7 +552,7 @@ class FlatString
                        var i = _first_byte
 
                        var my_items = _items
-                       var max = _last_byte
+                       var max = last_byte
 
                        while i <= max do
                                h = (h << 5) + h + my_items[i].to_i
@@ -574,7 +594,7 @@ private class FlatStringCharIterator
 
        var curr_pos: Int
 
-       init do max = target.length - 1
+       init do max = target._length - 1
 
        redef fun is_ok do return curr_pos <= max
 
@@ -641,7 +661,7 @@ private class FlatStringByteIterator
                curr_pos += tgt._first_byte
        end
 
-       redef fun is_ok do return curr_pos <= target._last_byte
+       redef fun is_ok do return curr_pos <= target.last_byte
 
        redef fun item do return target_items[curr_pos]
 
@@ -658,12 +678,11 @@ private class FlatStringByteView
 
        redef fun [](index)
        do
-               # Check that the index (+ _first_byte) is not larger than _last_byte
+               # Check that the index (+ _first_byte) is not larger than last_byte
                # In other terms, if the index is valid
-               assert index >= 0
-               var target = self.target
+               var target = _target
+               assert index >= 0 and index < target._bytelen
                var ind = index + target._first_byte
-               assert ind <= target._last_byte
                return target._items[ind]
        end
 
@@ -688,8 +707,6 @@ class FlatBuffer
 
        redef var bytes = new FlatBufferByteView(self) is lazy
 
-       redef var length = 0
-
        private var char_cache: Int = -1
 
        private var byte_cache: Int = -1
@@ -739,10 +756,10 @@ class FlatBuffer
 
        redef fun []=(index, item)
        do
-               assert index >= 0 and index <= length
+               assert index >= 0 and index <= _length
                if written then reset
                is_dirty = true
-               if index == length then
+               if index == _length then
                        add item
                        return
                end
@@ -758,7 +775,6 @@ class FlatBuffer
                        lshift_bytes(ip + clen, -size_diff)
                end
                _bytelen += size_diff
-               bytepos += size_diff
                it.set_char_at(ip, item)
        end
 
@@ -771,14 +787,14 @@ class FlatBuffer
                enlarge(bt + clen)
                _items.set_char_at(bt, c)
                _bytelen += clen
-               length += 1
+               _length += 1
        end
 
        redef fun clear do
                is_dirty = true
                if written then reset
                _bytelen = 0
-               length = 0
+               _length = 0
        end
 
        redef fun empty do return new Buffer
@@ -806,7 +822,7 @@ class FlatBuffer
                written = true
                var bln = _bytelen
                if bln == 0 then _items = new NativeString(1)
-               return new FlatString.full(_items, bln, 0, bln - 1, length)
+               return new FlatString.full(_items, bln, 0, _length)
        end
 
        redef fun to_cstring
@@ -815,7 +831,7 @@ class FlatBuffer
                        var bln = _bytelen
                        var new_native = new NativeString(bln + 1)
                        new_native[bln] = 0u8
-                       if length > 0 then _items.copy_to(new_native, bln, 0, 0)
+                       if _length > 0 then _items.copy_to(new_native, bln, 0, 0)
                        real_items = new_native
                        is_dirty = false
                end
@@ -837,7 +853,7 @@ class FlatBuffer
                self._items = items
                self.capacity = capacity
                self._bytelen = bytelen
-               self.length = length
+               self._length = length
        end
 
        # Create a new string copied from `s`.
@@ -850,7 +866,7 @@ class FlatBuffer
                        for i in substrings do i.as(FlatString)._items.copy_to(_items, i._bytelen, 0, 0)
                end
                _bytelen = s.bytelen
-               length = s.length
+               _length = s.length
                _capacity = _bytelen
                written = true
        end
@@ -878,7 +894,7 @@ class FlatBuffer
                        return
                end
                _bytelen = nln
-               length += s.length
+               _length += s.length
        end
 
        # Copies the content of self in `dest`
@@ -895,7 +911,7 @@ class FlatBuffer
        do
                assert count >= 0
                if from < 0 then from = 0
-               if (from + count) > length then count = length - from
+               if (from + count) > _length then count = _length - from
                if count <= 0 then return new Buffer
                var its = _items
                var bytefrom = its.char_to_byte_index(from)
@@ -918,7 +934,7 @@ class FlatBuffer
        redef fun times(repeats)
        do
                var bln = _bytelen
-               var x = new FlatString.full(_items, bln, 0, bln - 1, length)
+               var x = new FlatString.full(_items, bln, 0, _length)
                for i in [1 .. repeats[ do
                        append(x)
                end
@@ -927,13 +943,13 @@ class FlatBuffer
        redef fun upper
        do
                if written then reset
-               for i in [0 .. length[ do self[i] = self[i].to_upper
+               for i in [0 .. _length[ do self[i] = self[i].to_upper
        end
 
        redef fun lower
        do
                if written then reset
-               for i in [0 .. length[ do self[i] = self[i].to_lower
+               for i in [0 .. _length[ do self[i] = self[i].to_lower
        end
 end
 
@@ -1044,7 +1060,7 @@ private class FlatBufferCharView
        redef fun append(s)
        do
                var s_length = s.length
-               if target.capacity < s.length then enlarge(s_length + target.length)
+               if target.capacity < s.length then enlarge(s_length + target._length)
                for i in s do target.add i
        end
 
@@ -1063,7 +1079,7 @@ private class FlatBufferCharIterator
 
        var curr_pos: Int
 
-       init do max = target.length - 1
+       init do max = target._length - 1
 
        redef fun index do return curr_pos
 
@@ -1089,7 +1105,12 @@ redef class NativeString
        end
 
        redef fun to_s_full(bytelen, unilen) do
-               return new FlatString.full(self, bytelen, 0, bytelen - 1, unilen)
+               return new FlatString.full(self, bytelen, 0, unilen)
+       end
+
+       redef fun to_s_unsafe(len) do
+               if len == null then len = cstring_length
+               return new FlatString.with_infos(self, len, 0)
        end
 
        # Returns `self` as a new String.
@@ -1100,7 +1121,7 @@ redef class NativeString
                if r.items != self then return r
                var new_self = new NativeString(length + 1)
                copy_to(new_self, length, 0, 0)
-               var str = new FlatString.with_infos(new_self, length, 0, length - 1)
+               var str = new FlatString.with_infos(new_self, length, 0)
                new_self[length] = 0u8
                str.to_cstring = new_self
                return str
@@ -1112,8 +1133,23 @@ redef class NativeString
                var end_length = len
                var pos = 0
                var chr_ln = 0
-               while pos < len do
+               var rem = len
+               while rem > 0 do
+                       while rem >= 4 do
+                               var i = fetch_4_chars(pos)
+                               if i & 0x80808080 != 0 then break
+                               pos += 4
+                               chr_ln += 4
+                               rem -= 4
+                       end
+                       if rem == 0 then break
                        var b = self[pos]
+                       if b & 0x80u8 == 0x00u8 then
+                               pos += 1
+                               chr_ln += 1
+                               rem -= 1
+                               continue
+                       end
                        var nxst = length_of_char_at(pos)
                        var ok_st: Bool
                        if nxst == 1 then
@@ -1130,6 +1166,7 @@ redef class NativeString
                                replacements.add pos
                                end_length += 2
                                pos += 1
+                               rem -= 1
                                chr_ln += 1
                                continue
                        end
@@ -1152,9 +1189,12 @@ redef class NativeString
                                end_length += 2
                                pos += 1
                                chr_ln += 1
+                               rem -= 1
                                continue
                        end
-                       pos += c.u8char_len
+                       var clen = c.u8char_len
+                       pos += clen
+                       rem -= clen
                        chr_ln += 1
                end
                var ret = self
@@ -1178,7 +1218,7 @@ redef class NativeString
                        end
                        copy_to(ret, len - old_repl, old_repl, off)
                end
-               return new FlatString.full(ret, end_length, 0, end_length - 1, chr_ln)
+               return new FlatString.full(ret, end_length, 0, chr_ln)
        end
 
        # Sets the next bytes at position `pos` to the value of `c`, encoded in UTF-8
@@ -1236,7 +1276,7 @@ redef class Int
                var ns = new NativeString(nslen + 1)
                ns[nslen] = 0u8
                native_int_to_s(ns, nslen + 1)
-               return new FlatString.full(ns, nslen, 0, nslen - 1, nslen)
+               return new FlatString.full(ns, nslen, 0, nslen)
        end
 end
 
@@ -1245,7 +1285,7 @@ redef class Array[E]
        # Fast implementation
        redef fun plain_to_s
        do
-               var l = length
+               var l = _length
                if l == 0 then return ""
                var its = _items.as(not null)
                var first = its[0]
@@ -1286,7 +1326,7 @@ redef class Array[E]
                        end
                        i += 1
                end
-               return new FlatString.with_infos(ns, sl, 0, sl - 1)
+               return new FlatString.with_infos(ns, sl, 0)
        end
 end
 
@@ -1323,7 +1363,7 @@ redef class NativeArray[E]
                        end
                        i += 1
                end
-               return new FlatString.with_infos(ns, sl, 0, sl - 1)
+               return new FlatString.with_infos(ns, sl, 0)
        end
 end