X-Git-Url: http://nitlanguage.org

diff --git a/lib/core/text/abstract_text.nit b/lib/core/text/abstract_text.nit
index 1fcb0d9..fc8ec5b 100644
--- a/lib/core/text/abstract_text.nit
+++ b/lib/core/text/abstract_text.nit
@@ -68,7 +68,7 @@ abstract class Text
 	fun substring(from: Int, count: Int): SELFTYPE is abstract
 
 	# Iterates on the substrings of self if any
-	fun substrings: Iterator[FlatText] is abstract
+	private fun substrings: Iterator[FlatText] is abstract
 
 	# Is the current Text empty (== "")
 	#
@@ -248,7 +248,17 @@ abstract class Text
 	# If `self` contains only digits and alpha <= 'f', return the corresponding integer.
 	#
 	#     assert "ff".to_hex == 255
-	fun to_hex: Int do return a_to(16)
+	fun to_hex(pos, ln: nullable Int): Int do
+		var res = 0
+		if pos == null then pos = 0
+		if ln == null then ln = length - pos
+		var max = pos + ln
+		for i in [pos .. max[ do
+			res <<= 4
+			res += self[i].from_hex
+		end
+		return res
+	end
 
 	# If `self` contains only digits <= '7', return the corresponding integer.
 	#
@@ -718,6 +728,49 @@ abstract class Text
 		return res.to_s
 	end
 
+	# Returns `self` with all characters escaped with their UTF-16 representation
+	#
+	#     assert "Aèあ𐏓".escape_to_utf16 == "\\u0041\\u00e8\\u3042\\ud800\\udfd3"
+	fun escape_to_utf16: String do
+		var buf = new Buffer
+		for i in chars do buf.append i.escape_to_utf16
+		return buf.to_s
+	end
+
+	# Returns the Unicode char escaped by `self`
+	#
+	#     assert "\\u0041".from_utf16_escape == 'A'
+	#     assert "\\ud800\\udfd3".from_utf16_escape == '𐏓'
+	#     assert "\\u00e8".from_utf16_escape == 'è'
+	#     assert "\\u3042".from_utf16_escape == 'あ'
+	fun from_utf16_escape(pos, ln: nullable Int): Char do
+		if pos == null then pos = 0
+		if ln == null then ln = length - pos
+		if ln < 6 then return 0xFFFD.code_point
+		var cp = from_utf16_digit(pos + 2)
+		if cp < 0xD800 then return cp.code_point
+		if cp > 0xDFFF then return cp.code_point
+		if cp > 0xDBFF then return 0xFFFD.code_point
+		if ln == 6 then return 0xFFFD.code_point
+		if ln < 12 then return 0xFFFD.code_point
+		cp <<= 16
+		cp += from_utf16_digit(pos + 8)
+		var cplo = cp & 0xFFFF
+		if cplo < 0xDC00 then return 0xFFFD.code_point
+		if cplo > 0xDFFF then return 0xFFFD.code_point
+		return cp.from_utf16_surr.code_point
+	end
+
+	# Returns a UTF-16 escape value
+	#
+	#     var s = "\\ud800\\udfd3"
+	#     assert s.from_utf16_digit(2) == 0xD800
+	#     assert s.from_utf16_digit(8) == 0xDFD3
+	fun from_utf16_digit(pos: nullable Int): Int do
+		if pos == null then pos = 0
+		return to_hex(pos, 4)
+	end
+
 	# Encode `self` to percent (or URL) encoding
 	#
 	#     assert "aBc09-._~".to_percent_encoding == "aBc09-._~"
@@ -942,6 +995,65 @@ abstract class Text
 		return s.plain_to_s
 	end
 
+	# Return the Levenshtein distance between two strings
+	#
+	# ~~~
+	# assert "abcd".levenshtein_distance("abcd") == 0
+	# assert "".levenshtein_distance("abcd")     == 4
+	# assert "abcd".levenshtein_distance("")     == 4
+	# assert "abcd".levenshtein_distance("xyz")  == 4
+	# assert "abcd".levenshtein_distance("xbdy") == 3
+	# ~~~
+	fun levenshtein_distance(other: String): Int
+	do
+		var slen = self.length
+		var olen = other.length
+
+		# fast cases
+		if slen == 0 then return olen
+		if olen == 0 then return slen
+		if self == other then return 0
+
+		# previous row of distances
+		var v0 = new Array[Int].with_capacity(olen+1)
+
+		# current row of distances
+		var v1 = new Array[Int].with_capacity(olen+1)
+
+		for j in [0..olen] do
+			# prefix insert cost
+			v0[j] = j
+		end
+
+		for i in [0..slen[ do
+
+			# prefix delete cost
+			v1[0] = i + 1
+
+			for j in [0..olen[ do
+				# delete cost
+				var cost1 = v1[j] + 1
+				# insert cost
+				var cost2 = v0[j + 1] + 1
+				# same char cost (+0)
+				var cost3 = v0[j]
+				# change cost
+				if self[i] != other[j] then cost3 += 1
+				# keep the min
+				v1[j+1] = cost1.min(cost2).min(cost3)
+			end
+
+			# Switch columns:
+			# * v1 become v0 in the next iteration
+			# * old v0 is reused as the new v1
+			var tmp = v1
+			v1 = v0
+			v0 = tmp
+		end
+
+		return v0[olen]
+	end
+
 	# Copies `n` bytes from `self` at `src_offset` into `dest` starting at `dest_offset`
 	#
 	# Basically a high-level synonym of NativeString::copy_to
@@ -973,10 +1085,7 @@ abstract class FlatText
 	#
 	# Warning : Might be void in some subclasses, be sure to check
 	# if set before using it.
-	private var items: NativeString is noinit
-
-	# Real items, used as cache for to_cstring is called
-	private var real_items: nullable NativeString = null
+	var items: NativeString is noinit
 
 	# Returns a char* starting at position `first_byte`
 	#
@@ -993,7 +1102,7 @@ abstract class FlatText
 	#
 	# As always, do not modify the content of the String in C code, if this is what you want
 	# copy locally the char* as Nit Strings are immutable.
-	private fun fast_cstring: NativeString is abstract
+	fun fast_cstring: NativeString is abstract
 
 	redef var length = 0
 
@@ -1571,6 +1680,12 @@ redef class Char
 	#     assert 'ま'.bytes == [0xE3u8, 0x81u8, 0xBEu8]
 	fun bytes: SequenceRead[Byte] do return to_s.bytes
 
+	# Is `self` an UTF-16 surrogate pair ?
+	fun is_surrogate: Bool do
+		var cp = code_point
+		return cp >= 0xD800 and cp <= 0xDFFF
+	end
+
 	# Length of `self` in a UTF-8 String
 	private fun u8char_len: Int do
 		var c = self.code_point
@@ -1590,6 +1705,46 @@ redef class Char
 		return ns.to_s_with_length(ln)
 	end
 
+	# Returns `self` escaped to UTF-16
+	#
+	# i.e. Represents `self`.`code_point` using UTF-16 codets escaped
+	# with a `\u`
+	#
+	#     assert 'A'.escape_to_utf16 == "\\u0041"
+	#     assert 'è'.escape_to_utf16 == "\\u00e8"
+	#     assert 'あ'.escape_to_utf16 == "\\u3042"
+	#     assert '𐏓'.escape_to_utf16 == "\\ud800\\udfd3"
+	fun escape_to_utf16: String do
+		var cp = code_point
+		var buf: Buffer
+		if cp < 0xD800 or (cp >= 0xE000 and cp <= 0xFFFF) then
+			buf = new Buffer.with_cap(6)
+			buf.append("\\u0000")
+			var hx = cp.to_hex
+			var outid = 5
+			for i in hx.chars.reverse_iterator do
+				buf[outid] = i
+				outid -= 1
+			end
+		else
+			buf = new Buffer.with_cap(12)
+			buf.append("\\u0000\\u0000")
+			var lo = (((cp - 0x10000) & 0x3FF) + 0xDC00).to_hex
+			var hi = ((((cp - 0x10000) & 0xFFC00) >> 10) + 0xD800).to_hex
+			var out = 2
+			for i in hi do
+				buf[out] = i
+				out += 1
+			end
+			out = 8
+			for i in lo do
+				buf[out] = i
+				out += 1
+			end
+		end
+		return buf.to_s
+	end
+
 	private fun u8char_tos(r: NativeString, len: Int) `{
 		r[len] = '\0';
 		switch(len){
@@ -1640,6 +1795,16 @@ redef class Char
 		return (self >= 'a' and self <= 'z') or (self >= 'A' and self <= 'Z')
 	end
 
+	# Is `self` an hexadecimal digit ?
+	#
+	#     assert 'A'.is_hexdigit
+	#     assert not 'G'.is_hexdigit
+	#     assert 'a'.is_hexdigit
+	#     assert not 'g'.is_hexdigit
+	#     assert '5'.is_hexdigit
+	fun is_hexdigit: Bool do return (self >= '0' and self <= '9') or (self >= 'A' and self <= 'F') or
+					(self >= 'a' and self <= 'f')
+
 	# Returns true if the char is an alpha or a numeric digit
 	#
 	#     assert 'a'.is_alphanumeric
@@ -1653,6 +1818,19 @@ redef class Char
 	do
 		return self.is_numeric or self.is_alpha
 	end
+
+	# Returns `self` to its int value
+	#
+	# REQUIRE: `is_hexdigit`
+	fun from_hex: Int do
+		if self >= '0' and self <= '9' then return code_point - 0x30
+		if self >= 'A' and self <= 'F' then return code_point - 0x37
+		if self >= 'a' and self <= 'f' then return code_point - 0x57
+		# Happens if self is not a hexdigit
+		assert self.is_hexdigit
+		# To make flow analysis happy
+		abort
+	end
 end
 
 redef class Collection[E]