From 88b376ca3d8496aa2a1b24b27b4dd8027557fc57 Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Wed, 10 Jun 2009 09:29:20 -0400
Subject: [PATCH] lib: Split collections into readable and writable

Map ->
  MapRead (r)
  Map (rw)
IndexedCollection ->
  IndexedCollectionRead (r)
  IndexedCollection (rw)
AbstractArray ->
  AbstractArrayRead (r)
  AbstractArray (rw)
String ->
  String (ro)
  Buffer (rw)

Signed-off-by: Jean Privat <jean@pryen.org>
---
 lib/opts.nit                         |    4 +-
 lib/standard/abstract_collection.nit |   83 ++++---
 lib/standard/array.nit               |  173 +++++++-------
 lib/standard/exec.nit                |    4 +-
 lib/standard/file.nit                |    4 +-
 lib/standard/hash.nit                |   10 +-
 lib/standard/list.nit                |    2 +-
 lib/standard/stream.nit              |   28 +--
 lib/standard/string.nit              |  436 +++++++++++++++++++---------------
 src/compiling/compiling.nit          |    4 +-
 src/compiling/compiling_global.nit   |    4 +-
 src/compiling/compiling_methods.nit  |    8 +-
 src/metamodel/partial_order.nit      |    4 +-
 src/metamodel/static_type.nit        |    8 +-
 src/nitc.nit                         |    2 +-
 src/nitdoc.nit                       |   30 +--
 src/parser/lexer.nit                 |    8 +-
 src/parser/xss/lexer.xss             |    8 +-
 src/syntax/mmbuilder.nit             |    9 +-
 src/utils.nit                        |    4 +-
 tests/bench_string_append.nit        |    4 +-
 tests/example_objet.nit              |   16 +-
 tests/example_point.nit              |    6 +-
 tests/example_procedural_string.nit  |    4 +-
 tests/example_string.nit             |    2 +-
 tests/example_time.nit               |    4 +-
 tests/sav/test_symbol.sav            |    2 +-
 tests/shootout_nsieve.nit            |    2 +-
 tests/test_create_more.nit           |    4 +-
 tests/test_isa.nit                   |    2 +-
 tests/test_refinement.nit            |    2 +-
 tests/test_string_long.nit           |    4 +-
 32 files changed, 478 insertions(+), 407 deletions(-)

diff --git a/lib/opts.nit b/lib/opts.nit
index b9e5ceb..81b9a98 100644
--- a/lib/opts.nit
+++ b/lib/opts.nit
@@ -57,14 +57,14 @@ class Option
 	# A pretty print for this help
 	meth pretty(off: Int): String
 	do
-		var text = "  "
+		var text = new Buffer.from("  ")
 		text.append(_names.join(", "))
 		text.append("  ")
 		var rest = off - text.length
 		if rest > 0 then text.append(" " * rest)
 		text.append(helptext)
 		#text.append(pretty_default)
-		return text
+		return text.to_s
 	end
 
 	meth pretty_default: String
diff --git a/lib/standard/abstract_collection.nit b/lib/standard/abstract_collection.nit
index 2ece03d..8f0a11d 100644
--- a/lib/standard/abstract_collection.nit
+++ b/lib/standard/abstract_collection.nit
@@ -227,6 +227,17 @@ special SimpleCollection[E]
 	redef meth remove_all(item) do remove(item)
 end
 
+interface MapRead[K, E]
+special Collection[E]
+	# Get the item at `key'.
+	meth [](key: K): E is abstract
+
+	# Is there an item at `key'.
+	meth has_key(key: K): Bool is abstract
+
+	redef meth iterator: MapIterator[K, E] is abstract
+end
+
 # Maps are associative collections: `key' -> `item'.
 #
 # The main operator over maps is [].
@@ -241,15 +252,10 @@ end
 #     map.has_key(u3)    # -> false
 interface Map[K, E]
 special RemovableCollection[E]
-	# Get the item at `key'.    
-	meth [](key: K): E is abstract
-
+special MapRead[K, E]
 	# Set the`item' at `key'.
 	meth []=(key: K, item: E) is abstract
 
-	# Is there an item at `key'.
-	meth has_key(key: K): Bool is abstract
-
 	# Remove the item at `key'
 	meth remove_at(key: K) is abstract
 
@@ -263,8 +269,6 @@ special RemovableCollection[E]
 			i.next
 		end
 	end
-
-	redef meth iterator: MapIterator[K, E] is abstract
 end
 
 # Iterators for Map.
@@ -274,35 +278,55 @@ special Iterator[E]
 	meth key: K is abstract
 
 	# Set a new `item' at `key'.
-	meth item=(item: E) is abstract
+	#meth item=(item: E) is abstract
 end
 
 # Indexed collection are ordoned collections.
 # The first item is 0. The last is `length'-1.
-interface IndexedCollection[E]
-special Map[Int, E]
-special SimpleCollection[E]
+interface IndexedCollectionRead[E]
+special MapRead[Int, E]
 	# Get the first item.
 	# Is equivalent with `self'[0].
-	redef meth first 
-	do 
+	redef meth first
+	do
 		assert not_empty: not is_empty
-		return self[0] 
+		return self[0]
 	end
 	
-	# Set the first item.
-	# Is equivalent with `self'[0] = `item'.
-	meth first=(item: E)
-	do self[0] = item end
-
 	# Get the last item.
 	# Is equivalent with `self'[`length'-1].
 	meth last: E
-	do 
+	do
 		assert not_empty: not is_empty
-		return self[length-1] 
+		return self[length-1]
 	end
 
+	# Return the index of the first occurence of `item'.
+	# Return -1 if `item' is not found
+	meth index_of(item: E): Int
+	do
+		var i = iterator
+		while i.is_ok do
+			if i.item == item then return i.index
+			i.next
+		end
+		return -1
+	end
+
+	redef meth iterator: IndexedIterator[E] is abstract
+end
+
+# Indexed collection are ordoned collections.
+# The first item is 0. The last is `length'-1.
+interface IndexedCollection[E]
+special IndexedCollectionRead[E]
+special Map[Int, E]
+special SimpleCollection[E]
+	# Set the first item.
+	# Is equivalent with `self'[0] = `item'.
+	meth first=(item: E)
+	do self[0] = item end
+
 	# Set the last item.
 	# Is equivalent with `self'[length-1] = `item'.
 	meth last=(item: E) 
@@ -334,19 +358,6 @@ special SimpleCollection[E]
 	# The second item become the first.
 	meth shift: E is abstract
 
-	# Return the index of the first occurence of `item'.
-	# Return -1 if `item' is not found
-	meth index_of(item: E): Int
-	do
-		var i = iterator
-		while i.is_ok do
-			if i.item == item then return i.index
-			i.next
-		end
-		return -1
-	end
-
-	redef meth iterator: IndexedIterator[E] is abstract
 end
 
 # Iterators on indexed collections.
@@ -386,7 +397,7 @@ class CoupleMapIterator[K, E]
 special MapIterator[K, E]
 	redef meth item do return _iter.item.second
 	
-	redef meth item=(e) do _iter.item.second = e
+	#redef meth item=(e) do _iter.item.second = e
 
 	redef meth key do return _iter.item.first
 
diff --git a/lib/standard/array.nit b/lib/standard/array.nit
index 78beeb3..1f90388 100644
--- a/lib/standard/array.nit
+++ b/lib/standard/array.nit
@@ -17,60 +17,13 @@ package array
 
 import abstract_collection
 
-# Resizeable one dimention array of objects.
-class AbstractArray[E]
-special IndexedCollection[E]
-	meth enlarge(cap: Int) is abstract
-
+# One dimention array of objects.
+class AbstractArrayRead[E]
+special IndexedCollectionRead[E]
 	# The current length
 	redef readable attr _length: Int = 0
-	
-	redef meth is_empty do return _length == 0
-
-	redef meth push(item) do add(item)
-	
-	redef meth pop
-	do
-		assert not_empty: not is_empty
-		var r = last
-		_length -= 1
-		return r
-	end
-
-	redef meth shift
-	do
-		assert not_empty: not is_empty
-		var r = first
-		var i = 1
-		var l = length
-		while i < l do
-			self[i-1] = self[i]
-			i += 1
-		end
-		_length = l - 1
-		return r
-	end
 
-	redef meth unshift(item)
-	do
-		var i = length - 1
-		while i > 0 do
-			self[i+1] = self[i]
-			i -= 1
-		end
-		self[0] = item
-	end
-
-	meth insert(item: E, pos: Int)
-	do
-		enlarge(length + 1)
-		copy_to(pos, length-pos, self, pos + 1)
-		self[pos] = item
-	end
-
-	redef meth add(item) do self[length] = item
-
-	redef meth clear do _length = 0
+	redef meth is_empty do return _length == 0
 
 	redef meth has(item)
 	do
@@ -149,30 +102,6 @@ special IndexedCollection[E]
 		return result
 	end
 
-	redef meth remove(item) do remove_at(index_of(item))
-
-	redef meth remove_all(item)
-	do
-		var i = index_of(item)
-		while i >= 0 do
-			remove_at(i)
-			i = index_of_from(item, i)
-		end
-	end
-
-	redef meth remove_at(i)
-	do
-		var l = length
-		if i >= 0 and i < l then
-			var j = i + 1
-			while j < l do
-				self[j-1] = self[j]
-				j += 1
-			end		
-			_length = l - 1 
-		end
-	end
-
 	protected meth copy_to(start: Int, len: Int, dest: AbstractArray[E], new_start: Int)
 	do
 		# TODO native one
@@ -211,7 +140,83 @@ special IndexedCollection[E]
 		return true
 	end
 end
-	
+
+# Resizeable one dimention array of objects.
+class AbstractArray[E]
+special AbstractArrayRead[E]
+special IndexedCollection[E]
+	meth enlarge(cap: Int) is abstract
+
+	redef meth push(item) do add(item)
+
+	redef meth pop
+	do
+		assert not_empty: not is_empty
+		var r = last
+		_length -= 1
+		return r
+	end
+
+	redef meth shift
+	do
+		assert not_empty: not is_empty
+		var r = first
+		var i = 1
+		var l = length
+		while i < l do
+			self[i-1] = self[i]
+			i += 1
+		end
+		_length = l - 1
+		return r
+	end
+
+	redef meth unshift(item)
+	do
+		var i = length - 1
+		while i > 0 do
+			self[i+1] = self[i]
+			i -= 1
+		end
+		self[0] = item
+	end
+
+	meth insert(item: E, pos: Int)
+	do
+		enlarge(length + 1)
+		copy_to(pos, length-pos, self, pos + 1)
+		self[pos] = item
+	end
+
+	redef meth add(item) do self[length] = item
+
+	redef meth clear do _length = 0
+
+	redef meth remove(item) do remove_at(index_of(item))
+
+	redef meth remove_all(item)
+	do
+		var i = index_of(item)
+		while i >= 0 do
+			remove_at(i)
+			i = index_of_from(item, i)
+		end
+	end
+
+	redef meth remove_at(i)
+	do
+		var l = length
+		if i >= 0 and i < l then
+			var j = i + 1
+			while j < l do
+				self[j-1] = self[j]
+				j += 1
+			end
+			_length = l - 1
+		end
+	end
+end
+
 # Resizeable one dimention array of objects.
 #
 # Arrays have a literal representation.
@@ -312,13 +317,13 @@ class ArrayIterator[E]
 special IndexedIterator[E]
 	redef meth item do return _array[_index]
 
-	redef meth item=(e) do _array[_index] = e
+	# redef meth item=(e) do _array[_index] = e
 
 	redef meth is_ok do return _index < _array.length
 
 	redef meth next do _index += 1
 
-	init(a: AbstractArray[E])
+	init(a: AbstractArrayRead[E])
 	do
 		assert not_nil: a != null
 		_array = a
@@ -326,7 +331,7 @@ special IndexedIterator[E]
 	end
 
 	redef readable attr _index: Int = 0
-	attr _array: AbstractArray[E]
+	attr _array: AbstractArrayRead[E]
 end
 
 # Others collections ##########################################################
@@ -397,7 +402,7 @@ end
 
 # Associative arrays implemented with an array of (key, value) pairs.
 class ArrayMap[K, E]
-special CoupleMap[K, E] 
+special CoupleMap[K, E]
 
 	# O(n)
 	redef meth [](key)
@@ -418,7 +423,7 @@ special CoupleMap[K, E]
 			_items[i].second = item
 		else
 			_items.push(new Couple[K,E](key, item))
-		end                
+		end
 	end
 
 	# O(n)
@@ -511,12 +516,12 @@ special CoupleMap[K, E]
 
 	# The last positive result given by a index(1) call
 	attr _last_index: Int = 0
-	
+
 	# Where is the `key' in `_item'?
 	# return -1 if not found
 	private meth index(key: K): Int
 	do
-		var l = _last_index 
+		var l = _last_index
 		if l < _items.length and _items[l].first == key then return l
 
 		var i = 0
@@ -532,7 +537,7 @@ special CoupleMap[K, E]
 
 	# A new empty map.
 	init
-	do 
+	do
 		_items = new Array[Couple[K,E]]
 	end
 end
diff --git a/lib/standard/exec.nit b/lib/standard/exec.nit
index c98a39c..72dd195 100644
--- a/lib/standard/exec.nit
+++ b/lib/standard/exec.nit
@@ -61,7 +61,7 @@ class Process
 	# Internal code to handle execusion
 	protected init execute(command: String, arguments: Array[String], pipeflags: Int)
 	do
-		var args = new String
+		var args = new Buffer
 		var l = 1 # Number of elements in args
 		args.append(command)
 		if arguments != null then
@@ -71,7 +71,7 @@ class Process
 			end
 			l += arguments.length
 		end
-		_data = basic_exec_execute(command.to_cstring, args.to_cstring, l, pipeflags)
+		_data = basic_exec_execute(command.to_cstring, args.to_s.to_cstring, l, pipeflags)
 	end
 	
 	attr _data: NativeProcess
diff --git a/lib/standard/file.nit b/lib/standard/file.nit
index 7dbf17a..e6df753 100644
--- a/lib/standard/file.nit
+++ b/lib/standard/file.nit
@@ -242,7 +242,7 @@ redef class String
 	meth mkdir
 	do
 		var dirs = self.split_with("/")
-		var path = new String
+		var path = new Buffer
 		if dirs.is_empty then return
 		if dirs[0].is_empty then
 			# it was a starting /
@@ -252,7 +252,7 @@ redef class String
 			if d.is_empty then continue
 			path.append(d)
 			path.add('/')
-			path.to_cstring.file_mkdir
+			path.to_s.to_cstring.file_mkdir
 		end
 	end
 end
diff --git a/lib/standard/hash.nit b/lib/standard/hash.nit
index 9d68891..af4ebd3 100644
--- a/lib/standard/hash.nit
+++ b/lib/standard/hash.nit
@@ -336,11 +336,11 @@ special MapIterator[K, V]
 		return _node.second
 	end
 
-	redef meth item=(value)
-	do
-		assert is_ok
-		_node.second = value
-	end
+	#redef meth item=(value)
+	#do
+	#	assert is_ok
+	#	_node.second = value
+	#end
 
 	redef meth key
 	do
diff --git a/lib/standard/list.nit b/lib/standard/list.nit
index 5ab2cf3..97caba4 100644
--- a/lib/standard/list.nit
+++ b/lib/standard/list.nit
@@ -245,7 +245,7 @@ class ListIterator[E]
 special IndexedIterator[E]
 	redef meth item do return _node.item
 
-	redef meth item=(e) do _node.item = e
+	# redef meth item=(e) do _node.item = e
 
 	redef meth is_ok do return not _node == null
 
diff --git a/lib/standard/stream.nit b/lib/standard/stream.nit
index 9046044..3204e84 100644
--- a/lib/standard/stream.nit
+++ b/lib/standard/stream.nit
@@ -30,7 +30,7 @@ special IOS
 	# Read at most i bytes
 	meth read(i: Int): String
 	do
-		var s = new String.with_capacity(i)
+		var s = new Buffer.with_capacity(i)
 		while i > 0 and not eof do
 			var c = read_char
 			if c >= 0 then
@@ -38,31 +38,31 @@ special IOS
 				i -= 1
 			end
 		end
-		return s
+		return s.to_s
 	end
 
 	# Read a string until the end of the line.
 	meth read_line: String
 	do
 		assert not eof
-		var s = new String
+		var s = new Buffer
 		append_line_to(s)
-		return s
+		return s.to_s
 	end
 
 	# Read all the stream until the eof.
 	meth read_all: String
 	do
-		var s = ""
+		var s = new Buffer
 		while not eof do
 			var c = read_char
 			if c >= 0 then s.add(c.ascii)
 		end
-		return s
+		return s.to_s
 	end
 
 	# Read a string until the end of the line and append it to `s'.
-	meth append_line_to(s: String)
+	meth append_line_to(s: Buffer)
 	do
 		while true do
 			var x = read_char
@@ -109,13 +109,13 @@ special IStream
 
 	redef meth read(i)
 	do
-		var s = new String.with_capacity(i)
+		var s = new Buffer.with_capacity(i)
 		var j = _buffer_pos
 		var k = _buffer.length
 		while i > 0 do
 			if j >= k then
 				fill_buffer
-				if eof then return s
+				if eof then return s.to_s
 				j = _buffer_pos
 				k = _buffer.length
 			end
@@ -126,12 +126,12 @@ special IStream
 			end
 		end
 		_buffer_pos = j
-		return s
+		return s.to_s
 	end
 
 	redef meth read_all
 	do
-		var s = ""
+		var s = new Buffer
 		while not eof do
 			var j = _buffer_pos
 			var k = _buffer.length
@@ -142,7 +142,7 @@ special IStream
 			_buffer_pos = j
 			fill_buffer
 		end
-		return s
+		return s.to_s
 	end   
 
 	redef meth append_line_to(s)
@@ -184,7 +184,7 @@ special IStream
 	redef meth eof do return _buffer_pos >= _buffer.length and end_reached
 
 	# The buffer
-	attr _buffer: String = null
+	attr _buffer: Buffer = null
 
 	# The current position in the buffer
 	attr _buffer_pos: Int = 0
@@ -198,7 +198,7 @@ special IStream
 	# Allocate a `_buffer' for a given `capacity'.
 	protected meth prepare_buffer(capacity: Int)
 	do
-		_buffer = new String.with_capacity(capacity)
+		_buffer = new Buffer.with_capacity(capacity)
 		_buffer_pos = 0 # need to read
 	end
 end
diff --git a/lib/standard/string.nit b/lib/standard/string.nit
index a9ebc63..3b0065c 100644
--- a/lib/standard/string.nit
+++ b/lib/standard/string.nit
@@ -20,88 +20,86 @@ intrude import array
 # String                                                                      #
 ###############################################################################
 
-# Strings are arrays of characters.
-class String
-special AbstractArray[Char]
-special Comparable
-special StringCapable
-	
-	redef type OTHER: String
+abstract class AbstractString
+special AbstractArrayRead[Char]
+	readable private attr _items: NativeString
 
 	redef meth [](index) do return _items[index]
 
-	redef meth []=(index, item)
+	# Create a substring.
+	#
+	# "abcd".substring(1, 2) 	# --> "bc"
+	# "abcd".substring(-1, 2)	# --> "a"
+	# "abcd".substring(1, 0)     # --> ""
+	# "abcd".substring(2, 5)     # --> "cd"
+	meth substring(from: Int, count: Int): String
 	do
-		if index == length then
-			add(item)
-			return
+		assert count >= 0
+		count += from
+		if from < 0 then from = 0
+		if count > length then count = length
+		if from < count then
+			var r = new Buffer.with_capacity(count - from)
+			while from < count do
+				r.push(_items[from])
+				from += 1
+			end
+			return r.to_s
+		else
+			return ""
 		end
-		assert index >= 0 and index < length
-		_items[index] = item
-	end
-
-	redef meth add(c)
-	do
-		if _capacity <= length then enlarge(length + 5)
-		_items[length] = c
-		_length += 1
 	end
 
-	redef meth enlarge(cap)
+	# Create a substring with the string beginning at the 'from' position
+	#
+	# "abcd".substring(1) 	# --> "bcd"
+	# "abcd".substring(-1)	# --> "abcd"
+	# "abcd".substring(2)     # --> "cd"
+	meth substring_from(from: Int): String
 	do
-		var c = _capacity
-		if cap <= c then return
-		while c <= cap do c = c * 2 + 2
-		var a = calloc_string(c)
-		_items.copy_to(a, length, 0, 0)
-		_items = a
-		_capacity = c
+		assert from < length
+		return substring(from, length - from)
 	end
 
-	redef meth append(s)
+	# is this string a substring of the 'of' string from pos 'pos'
+	#
+	# "bc".is_substring("abcd",1) 	# --> true
+	# "bc".is_substring("abcd",2) 	# --> false
+	meth has_substring(str: String, pos: Int): Bool
 	do
-		if s isa String then
-			var sl = s.length
-			if _capacity < length + sl then enlarge(length + sl)
-			s.items.copy_to(_items, sl, 0, length)
-			_length += sl
-		else
-			super
+		var itsindex = str.length - 1
+		var myindex = pos + itsindex
+		var myitems = _items
+		var itsitems = str._items
+		if myindex > length or itsindex > myindex  then return false
+		while itsindex > 0 do
+			if myitems[myindex] != itsitems[itsindex] then return false
+			myindex -= myindex
+			itsindex -= itsindex
 		end
+		return true
 	end
 
-	# The concatenation of `self' with `r'
-	meth +(s: String): String
-	do
-		var r = new String.with_capacity(length + s.length)
-		r.append(self)
-		r.append(s)
-		return r
-	end
-	
-	# i repetitions of self
-	meth *(i: Int): String
-	do
-		assert i >= 0
-		var r = new String.with_capacity(length * i)
-		while i > 0 do
-			r.append(self)
-			i -= 1
-		end
-		return r
-	end
+	# Is this string prefixed by 'prefix'
+	#
+	# "abc".is_prefix("abcd") 	# --> true
+	# "bc".is_prefix("abcd") 	# --> false
+	meth has_prefix(prefix: String): Bool do return has_substring(prefix,0)
 
-	# Clone.
-	redef meth to_s: String do return new String.from(self)
+	# Is this string suffixed by 'suffix'
+	#
+	# "abcd".has_suffix("abc") 	# --> false
+	# "abcd".has_suffix("bcd") 	# --> true
+	meth has_suffix(suffix: String): Bool do return has_substring(suffix, length - suffix.length)
 
 	# If `self' contains only digits, return the corresponding integer
 	meth to_i: Int
 	do
 		# Shortcut
-		return to_cstring.atoi
+		return to_s.to_cstring.atoi
 	end
 
-	# If `self' contains only digits and alpha <= 'f', return the corresponding integer. 
+	# If `self' contains only digits and alpha <= 'f', return the corresponding integer.
 	meth to_hex: Int do return a_to(16)
 
 	# If `self' contains only digits and letters, return the corresponding integer in a given base
@@ -109,7 +107,7 @@ special StringCapable
 	do
 		var i = 0
 		var neg = false
-		
+
 		for c in self
 		do
 			var v = c.to_i
@@ -132,79 +130,185 @@ special StringCapable
 		end
 	end
 
+	# String to upper case
+	meth to_upper: String
+	do
+		var s = new Buffer.with_capacity(length)
+		for i in self do s.add(i.to_upper)
+		return s.to_s
+	end
+
+	# String to lower case
+	meth to_lower : String
+	do
+		var s = new Buffer.with_capacity(length)
+		for i in self do s.add(i.to_lower)
+		return s.to_s
+	end
+
+
+	redef meth output
+	do
+		var i = 0
+		while i < length do
+			_items[i].output
+			i += 1
+		end
+	end
+end
+
+
+class String
+special Comparable
+special AbstractString
+	redef type OTHER: String
+
+	# Create a new string from a given char *.
+	init with_native(nat: NativeString, size: Int)
+	do
+		assert size >= 0
+		_items = nat
+		_length = size
+	end
+
+	# Create a new string from a null terminated char *.
+	init from_cstring(str: NativeString)
+	do
+		var size = str.cstring_length
+		_items = str
+		_length = size
+	end
+
 	# Return a null terminated char *
 	meth to_cstring: NativeString
 	do
-		self[length] = '\0'
-		_length -= 1
 		return _items
 	end
 
-	# Create a substring.
-	#
-	# "abcd".substring(1, 2) 	# --> "bc"
-	# "abcd".substring(-1, 2)	# --> "a"
-	# "abcd".substring(1, 0)     # --> ""
-	# "abcd".substring(2, 5)     # --> "cd"
-	meth substring(from: Int, count: Int): String
+	redef meth ==(o)
 	do
-		assert count >= 0
-		count += from
-		if from < 0 then from = 0
-		if count > length then count = length
-		if from < count then
-			var r = new String.with_capacity(count - from)
-			while from < count do
-				r.push(_items[from])
-				from += 1
+		if not o isa String or o is null then return false
+		assert o isa String
+		var l = length
+		if o.length != l then return false
+		var i = 0
+		var it = _items
+		var oit = o._items
+		while i < l do
+			if it[i] != oit[i] then return false
+			i += 1
+		end
+		return true
+	end
+
+	redef meth <(s)
+	do
+		var i = 0
+		var l1 = length
+		var l2 = s.length
+		var n1 = _items
+		var n2 = s._items
+		while i < l1 and i < l2 do
+			var c1 = n1[i].ascii
+			var c2 = n2[i].ascii
+			if c1 < c2 then
+				return true
+			else if c2 < c1 then
+				return false
 			end
-			return r
+			i += 1
+		end
+		if l1 < l2 then
+			return true
 		else
-			return ""
+			return false
 		end
 	end
 
-	# Create a substring with the string beginning at the 'from' position
-	#
-	# "abcd".substring(1) 	# --> "bcd"
-	# "abcd".substring(-1)	# --> "abcd"
-	# "abcd".substring(2)     # --> "cd"
-	meth substring_from(from: Int): String
+	# The concatenation of `self' with `r'
+	meth +(s: String): String
 	do
-		assert from < length
-		return substring(from, length - from)
+		var r = new Buffer.with_capacity(length + s.length)
+		r.append(self)
+		r.append(s)
+		return r.to_s
 	end
 
-	# is this string a substring of the 'of' string from pos 'pos'
-	#
-	# "bc".is_substring("abcd",1) 	# --> true
-	# "bc".is_substring("abcd",2) 	# --> false
-	meth has_substring(str: String, pos: Int): Bool
+	# i repetitions of self
+	meth *(i: Int): String
 	do
-		var itsindex = str.length - 1
-		var myindex = pos + itsindex
-		var myitems = _items
-		var itsitems = str._items
-		if myindex > length or itsindex > myindex  then return false
-		while itsindex > 0 do
-			if myitems[myindex] != itsitems[itsindex] then return false
-			myindex -= myindex
-			itsindex -= itsindex
+		assert i >= 0
+		var r = new Buffer.with_capacity(length * i)
+		while i > 0 do
+			r.append(self)
+			i -= 1
 		end
-		return true
+		return r.to_s
 	end
 
-	# Is this string prefixed by 'prefix'
-	#
-	# "abc".is_prefix("abcd") 	# --> true
-	# "bc".is_prefix("abcd") 	# --> false
-	meth has_prefix(prefix: String): Bool do return has_substring(prefix,0)
+	redef meth to_s do return self
+end
 
-	# Is this string suffixed by 'suffix'
-	#
-	# "abcd".has_suffix("abc") 	# --> false
-	# "abcd".has_suffix("bcd") 	# --> true
-	meth has_suffix(suffix: String): Bool do return has_substring(suffix, length - suffix.length)
+# Strings are arrays of characters.
+class Buffer
+special AbstractString
+special Comparable
+special StringCapable
+special AbstractArray[Char]
+
+	redef type OTHER: String
+
+	redef meth []=(index, item)
+	do
+		if index == length then
+			add(item)
+			return
+		end
+		assert index >= 0 and index < length
+		_items[index] = item
+	end
+
+	redef meth add(c)
+	do
+		if _capacity <= length then enlarge(length + 5)
+		_items[length] = c
+		_length += 1
+	end
+
+	redef meth enlarge(cap)
+	do
+		var c = _capacity
+		if cap <= c then return
+		while c <= cap do c = c * 2 + 2
+		var a = calloc_string(c+1)
+		_items.copy_to(a, length, 0, 0)
+		_items = a
+		_capacity = c
+	end
+
+	redef meth append(s)
+	do
+		if s isa String then
+			var sl = s.length
+			if _capacity < length + sl then enlarge(length + sl)
+			s.items.copy_to(_items, sl, 0, length)
+			_length += sl
+		else
+			super
+		end
+	end
+
+	redef meth to_s: String
+	do
+		var l = length
+		var a = calloc_string(l+1)
+		_items.copy_to(a, l, 0, 0)
+
+		# Ensure the afterlast byte is '\0' to nul-terminated char *
+		a[length] = '\0'
+
+		return new String.with_native(a, length)
+	end
 
 	redef meth <(s)
 	do
@@ -247,54 +351,15 @@ special StringCapable
 	do
 		assert cap >= 0
 		# _items = new NativeString.calloc(cap)
-		_items = calloc_string(cap)
+		_items = calloc_string(cap+1)
 		_capacity = cap
 		_length = 0
 	end
 
-	# Create a new string from a given char *.
-	init with_native(nat: NativeString, size: Int)
-	do
-		assert size >= 0
-		_items = nat
-		_capacity = size
-		_length = size
-	end
-
-	# Create a new string from a null terminated char *.
-	init from_cstring(str: NativeString)
-	do
-		var size = str.cstring_length
-		_items = str
-		_capacity = size + 1 # Since there is a trailing \n
-		_length = size
-	end
-
-	# Create a string of `count' chararter `c'
-	init filled_with(c: Char, count: Int)
-	do
-		with_capacity(count)
-		var i = 0
-		while i < count do
-			_items[i] = c
-			i += 1
-		end
-		_length = count
-	end
-
-	redef meth output
-	do
-		var i = 0
-		while i < length do
-			_items[i].output
-			i += 1
-		end
-	end
-
 	redef meth ==(o)
 	do
-		if not o isa String or o is null then return false
-		assert o isa String
+		if not o isa Buffer or o is null then return false
+		assert o isa Buffer
 		var l = length
 		if o.length != l then return false
 		var i = 0
@@ -307,23 +372,6 @@ special StringCapable
 		return true
 	end
 
-	# String to upper case
-	meth to_upper: String
-	do
-		var s = new String.with_capacity(length)
-		for i in self do s.add(i.to_upper)
-		return s
-	end
-
-	# String to lower case
-	meth to_lower : String
-	do
-		var s = new String.with_capacity(length)
-		for i in self do s.add(i.to_lower)
-		return s
-	end
-
-	readable private attr _items: NativeString 
 	readable private attr _capacity: Int 
 end
 
@@ -342,7 +390,7 @@ redef class Object
 	meth inspect: String
 	do
 		var r = inspect_head
-		r.add('>')
+		# r.add('>')
 		return r
 	end
 
@@ -371,7 +419,7 @@ redef class Bool
 end
 
 redef class Int
-	meth fill_string(s: String, base: Int, signed: Bool)
+	meth fill_buffer(s: Buffer, base: Int, signed: Bool)
 	# Fill `s' with the digits in base 'base' of `self' (and with the '-' sign if 'signed' and negative).
 	# assume < to_c max const of char
 	do
@@ -405,9 +453,9 @@ redef class Int
 	meth to_base(base: Int, signed: Bool): String
 	do
 		var l = digit_count(base)
-		var s = new String.filled_with(' ', l)
-		fill_string(s, base, signed)
-		return s
+		var s = new Buffer.from(" " * l)
+		fill_buffer(s, base, signed)
+		return s.to_s
 	end
 end
 
@@ -433,9 +481,9 @@ end
 redef class Char
 	redef meth to_s
 	do
-		var s = new String.with_capacity(1)
+		var s = new Buffer.with_capacity(1)
 		s[0] = self
-		return s
+		return s.to_s
 	end
 end
 
@@ -443,9 +491,9 @@ redef class Collection[E]
 	# Concatenate elements.
 	redef meth to_s
 	do
-		var s = new String
+		var s = new Buffer
 		for e in self do if e != null then s.append(e.to_s)
-		return s
+		return s.to_s
 	end
 
 	# Concatenate and separate each elements with `sep'. 
@@ -453,7 +501,7 @@ redef class Collection[E]
 	do
 		if is_empty then return ""
 		
-		var s = new String # Result
+		var s = new Buffer # Result
 
 		# Concat first item
 		var i = iterator
@@ -468,7 +516,23 @@ redef class Collection[E]
 			if e != null then s.append(e.to_s)
 			i.next
 		end
-		return s
+		return s.to_s
+	end
+end
+
+redef class Array[E]
+	# Fast implementation
+	redef meth to_s
+	do
+		var s = new Buffer
+		var i = 0
+		var l = length
+		while i < l do
+			var e = self[i]
+			if e != null then s.append(e.to_s)
+			i += 1
+		end
+		return s.to_s
 	end
 end
 
@@ -478,7 +542,7 @@ redef class Map[K,V]
 	do
 		if is_empty then return ""
 		
-		var s = new String # Result
+		var s = new Buffer # Result
 
 		# Concat first item
 		var i = iterator
@@ -495,7 +559,7 @@ redef class Map[K,V]
 			if e != null then s.append("{k}{couple_sep}{e}")
 			i.next
 		end
-		return s
+		return s.to_s
 	end
 end
 
diff --git a/src/compiling/compiling.nit b/src/compiling/compiling.nit
index a74118b..5af27e8 100644
--- a/src/compiling/compiling.nit
+++ b/src/compiling/compiling.nit
@@ -48,7 +48,7 @@ redef class MMSrcModule
 			if (native_name + "_nit.h").file_exists then
 				includes.add("-I {native_name.dirname}")
 			end
-			native_name.append("_nit.c")
+			native_name += "_nit.c"
 			if native_name.file_exists then files.add(native_name)
 		end
 
@@ -103,7 +103,7 @@ redef class MMSrcModule
 		v.global_analysis = ga
 		v.add_decl("#include <nit_common.h>")
 		var native_name = filename.strip_extension(".nit")
-		native_name.append("_nit.h")
+		native_name += ("_nit.h")
 		if native_name.file_exists then v.add_decl("#include <{native_name.basename("")}>")
 		declare_class_tables_to_c(v)
 		compile_mod_to_c(v)
diff --git a/src/compiling/compiling_global.nit b/src/compiling/compiling_global.nit
index 65c6ca0..f883907 100644
--- a/src/compiling/compiling_global.nit
+++ b/src/compiling/compiling_global.nit
@@ -421,7 +421,7 @@ redef class MMSrcModule
 		for c in local_classes do
 			c.compile_tables_to_c(v)
 		end
-		var s = "classtable_t TAG2VFT[4] = \{NULL"
+		var s = new Buffer.from("classtable_t TAG2VFT[4] = \{NULL")
 		for t in ["Int","Char","Bool"] do
 			if has_global_class_named(t.to_symbol) then
 				s.append(", (const classtable_t)VFT_{t}")
@@ -430,7 +430,7 @@ redef class MMSrcModule
 			end
 		end
 		s.append("};")
-		v.add_instr(s)
+		v.add_instr(s.to_s)
 	end
 
 	# Declare class table (for _sep.h)
diff --git a/src/compiling/compiling_methods.nit b/src/compiling/compiling_methods.nit
index 4556ba2..1253a51 100644
--- a/src/compiling/compiling_methods.nit
+++ b/src/compiling/compiling_methods.nit
@@ -73,12 +73,12 @@ redef class CompilerVisitor
 	# Generate an fprintf to display an error location
 	meth printf_locate_error(node: PNode): String
 	do
-		var s = "fprintf(stderr, \""
+		var s = new Buffer.from("fprintf(stderr, \"")
 		if nmc != null then s.append(" in %s")
 		s.append(" (%s:%d)\\n\", ")
 		if nmc != null then s.append("LOCATE_{nmc.method.cname}, ")
 		s.append("LOCATE_{module.name}, {node.line_number});")
-		return s
+		return s.to_s
 	end
 
 	redef init(module: MMSrcModule)
@@ -1194,7 +1194,7 @@ redef class AStringFormExpr
 	do
 		var len = 0
 		var str = string_text
-		var res = new String
+		var res = new Buffer
 		var i = 0
 		while i < str.length do
 			var c = str[i]
@@ -1210,7 +1210,7 @@ redef class AStringFormExpr
 			res.add(c)
 			i = i + 1
 		end
-		_cstring = res
+		_cstring = res.to_s
 		_cstring_length = len
 	end
 end
diff --git a/src/metamodel/partial_order.nit b/src/metamodel/partial_order.nit
index 42a0525..4960a51 100644
--- a/src/metamodel/partial_order.nit
+++ b/src/metamodel/partial_order.nit
@@ -68,7 +68,7 @@ special Collection[E]
 	# Return a dot representation
 	meth to_dot: String
 	do
-		var s = new String
+		var s = new Buffer
 		s.append(to_dot_header)
 		for e in _elements do
 			s.append(to_dot_node(e.value))
@@ -77,7 +77,7 @@ special Collection[E]
 			end
 		end
 		s.append("}\n")
-		return s
+		return s.to_s
 	end
 
 	# Called to display the header
diff --git a/src/metamodel/static_type.nit b/src/metamodel/static_type.nit
index 627fe9e..6cf53b7 100644
--- a/src/metamodel/static_type.nit
+++ b/src/metamodel/static_type.nit
@@ -122,7 +122,7 @@ class MMSignature
 
 	redef meth to_s
 	do
-		var s: String
+		var s = new Buffer
 		if _params != null and _params.length > 0 then
 			var tmp: String
 			var a = new Array[String].with_capacity(_params.length)
@@ -132,14 +132,12 @@ class MMSignature
 				#a.add("{pn}: {p}")
 				a.add(p.to_s)
 			end
-			s = "({a.join(",")})"
-		else
-			s = ""
+			s.append("({a.join(",")})")
 		end
 		if _return_type != null then
 			s.append(": {_return_type}")
 		end
-		return s
+		return s.to_s
 	end
 
 	# Adapt the signature to a different receiver
diff --git a/src/nitc.nit b/src/nitc.nit
index 57ce45e..5c65f1f 100644
--- a/src/nitc.nit
+++ b/src/nitc.nit
@@ -57,7 +57,7 @@ special AbstractCompiler
 				compdir = ".nit_compile"
 			end
 		end
-		compdir.append(ext_prefix)
+		compdir += ext_prefix
 
 		clibdir = opt_clibdir.value
 		if clibdir == null then
diff --git a/src/nitdoc.nit b/src/nitdoc.nit
index 9f55979..30d29da 100644
--- a/src/nitdoc.nit
+++ b/src/nitdoc.nit
@@ -425,7 +425,7 @@ special MMEntity
 
 	redef meth prototype_head(dctx)
 	do
-		var res = ""
+		var res = new Buffer
 		var intro_class = known_intro_class(dctx)
 		var is_redef = local_class != intro_class
 
@@ -444,12 +444,13 @@ special MMEntity
 				res.append(" {intro_class.module.html_link(dctx)}::")
 			end
 		end
-		return res
+		return res.to_s
 	end
 
 	redef meth prototype_body(dctx)
 	do
-		var res = signature.to_html(dctx)
+		var res = new Buffer
+		res.append(signature.to_html(dctx))
 		var s = self
 		if s.node != null then
 			if s.node isa ADeferredMethPropdef then
@@ -458,7 +459,7 @@ special MMEntity
 				res.append(" is intern")
 			end
 		end
-		return res
+		return res.to_s
 	end
 
 	redef meth need_doc(dctx)
@@ -675,11 +676,11 @@ redef class ADoc
 	# Html transcription of the doc
 	meth to_html: String
 	do
-		var res = new String
+		var res = new Buffer
 		for c in n_comment do
 			res.append(c.text.substring_from(1))
 		end
-		return res
+		return res.to_s
 	end
 
 	# Oneliner transcription of the doc
@@ -726,19 +727,19 @@ special MMEntity
 
 	redef meth prototype_head(dctx)
 	do
-		var res = ""
+		var res = new Buffer
 		var ki = known_intro(dctx)
 		var is_redef = ki != self
 		if is_redef then res.append("redef ")
 		if global.visibility_level == 3 then res.append("private ")
 		res.append("class ")
 		if is_redef then res.append("{ki.module.html_link(dctx)}::")
-		return res
+		return res.to_s
 	end
 
 	redef meth prototype_body(dctx)
 	do
-		var res = ""
+		var res = new Buffer
 		if arity > 0 then
 			res.append("[")
 			for i in [0..arity[ do
@@ -749,7 +750,7 @@ special MMEntity
 			end
 			res.append("]")
 		end
-		return res
+		return res.to_s
 	end
 
 	# Extract the doc of a class
@@ -1105,7 +1106,7 @@ redef class MMSignature
 	# Htlm transcription of the signature (with nested links)
 	meth to_html(dctx: DocContext): String
 	do
-		var res = new String
+		var res = new Buffer
 		if arity > 0 then
 			res.append("(")
 			res.append(self[0].html_link(dctx))
@@ -1119,7 +1120,7 @@ redef class MMSignature
 			res.append(": ")
 			res.append(return_type.html_link(dctx))
 		end
-		return res
+		return res.to_s
 	end
 end
 
@@ -1135,7 +1136,8 @@ end
 redef class MMTypeGeneric
 	redef meth html_link(dctx)
 	do
-		var res = local_class.html_link(dctx)
+		var res = new Buffer
+		res.append(local_class.html_link(dctx))
 		res.append("[")
 		res.append(params[0].html_link(dctx))
 		for i in [1..params.length[ do
@@ -1143,7 +1145,7 @@ redef class MMTypeGeneric
 			res.append(params[i].html_link(dctx))
 		end
 		res.append("]")
-		return res
+		return res.to_s
 	end
 end
 
diff --git a/src/parser/lexer.nit b/src/parser/lexer.nit
index 8a7fb3d..bc2de48 100644
--- a/src/parser/lexer.nit
+++ b/src/parser/lexer.nit
@@ -1320,7 +1320,7 @@ class Lexer
 	attr _stream: IStream
 
 	# Pushback buffer to store unread character
-	attr _stream_buf: String
+	attr _stream_buf: Buffer
 
 	# Number of character stored in the pushback buffer
 	attr _stream_pos: Int
@@ -1338,7 +1338,7 @@ class Lexer
 	attr _eof: Bool = false
 
 	# Current working text read from the input stream
-	attr _text: String
+	attr _text: Buffer
 
 	# Constante state values
 	private meth state_initial: Int do return 0 end
@@ -1347,10 +1347,10 @@ class Lexer
 	init(stream: IStream, fname: String)
 	do
 		_filename = fname
-		_text = new String
+		_text = new Buffer
 		_stream = stream
 		_stream_pos = -1
-		_stream_buf = new String
+		_stream_buf = new Buffer
 		build_goto_table
 		build_accept_table
 	end
diff --git a/src/parser/xss/lexer.xss b/src/parser/xss/lexer.xss
index f3b3247..d962dce 100644
--- a/src/parser/xss/lexer.xss
+++ b/src/parser/xss/lexer.xss
@@ -34,7 +34,7 @@ class Lexer
 	attr _stream: IStream
 
 	# Pushback buffer to store unread character
-	attr _stream_buf: String
+	attr _stream_buf: Buffer
 
 	# Number of character stored in the pushback buffer
 	attr _stream_pos: Int
@@ -52,7 +52,7 @@ class Lexer
 	attr _eof: Bool = false
 
 	# Current working text read from the input stream
-	attr _text: String
+	attr _text: Buffer
 
 $ foreach {lexer_data/state}
 	# Constante state values
@@ -63,10 +63,10 @@ $ end foreach
 	init(stream: IStream, fname: String)
 	do
 		_filename = fname
-		_text = new String
+		_text = new Buffer
 		_stream = stream
 		_stream_pos = -1
-		_stream_buf = new String
+		_stream_buf = new Buffer
 		build_goto_table
 		build_accept_table
 	end
diff --git a/src/syntax/mmbuilder.nit b/src/syntax/mmbuilder.nit
index 038ab90..b59eaa9 100644
--- a/src/syntax/mmbuilder.nit
+++ b/src/syntax/mmbuilder.nit
@@ -1055,7 +1055,7 @@ end
 # Visitor used to build a full method name from multiple tokens
 private class MethidAccumulator
 special Visitor
-	readable attr _name: String 
+	readable attr _name: Buffer = new Buffer
 	redef meth visit(n)
 	do
 		if n isa Token then
@@ -1064,11 +1064,6 @@ special Visitor
 			n.visit_all(self)
 		end
 	end
-
-	init
-	do
-		_name = new String
-	end
 end
 
 redef class PMethid
@@ -1079,7 +1074,7 @@ redef class PMethid
 	do
 		var accumulator = new MethidAccumulator
 		accumulator.visit(self)
-		_name = accumulator.name.to_symbol
+		_name = accumulator.name.to_s.to_symbol
 		super
 	end
 end
diff --git a/src/utils.nit b/src/utils.nit
index 1aa727f..f8dbfbd 100644
--- a/src/utils.nit
+++ b/src/utils.nit
@@ -22,7 +22,7 @@ package utils
 meth cmangle(symbols: Symbol...): String
 do
 	var table = once cmangle_table
-	var res = new String
+	var res = new Buffer
 	for sym in symbols do
 		if not res.is_empty then
 			res.add('_')
@@ -52,7 +52,7 @@ do
 			end
 		end
 	end
-	return res
+	return res.to_s
 end
 
 # Build the table that associates character to mangle to string
diff --git a/tests/bench_string_append.nit b/tests/bench_string_append.nit
index 1856a7a..9f5944f 100644
--- a/tests/bench_string_append.nit
+++ b/tests/bench_string_append.nit
@@ -22,7 +22,7 @@ end
 var s = "*"
 var i = 0
 while i < n do
-	var s2 = "Je dis «"
+	var s2 = new Buffer.from("Je dis «")
 	s2.append(s)
 	s2.append("» et redis «")
 	s2.append(s)
@@ -30,7 +30,7 @@ while i < n do
 	s2.append(s)
 	s2.append(s)
 	s2.append("».\n")
-	s = s2
+	s = s2.to_s
 	i = i + 1
 end
 print("Je dis «Je dis".search_all_in(s).length)
diff --git a/tests/example_objet.nit b/tests/example_objet.nit
index db8bc4f..cc22a7c 100644
--- a/tests/example_objet.nit
+++ b/tests/example_objet.nit
@@ -101,9 +101,9 @@ private
 	do
 		# Les variables sont déclarées par "var", leur portée va de leur
 		# déclaration jusqu'au "end" correspondant
-		var s: String		# Là où on calcule le résultat
+		var s = new Buffer		# Là où on calcule le résultat
 		# Les chaînes littérales sont déclarées avec des guillemets
-		s = "*** Entrepôt "	# On initialise "s"
+		s.append("*** Entrepôt ")	# On initialise "s"
 		# puis on concatène des chaînes à "s"
 		s.append(_nom_)		# la méthode "append" concatène
 		s.append(" ***\n")
@@ -124,7 +124,7 @@ private
 			s.add('\n')	# "add" ajoute un caractère à la fin.
 			# Comme en C, les caractères sont entre simples cotes.
 		end
-		return s
+		return s.to_s
 	end
 
 
@@ -218,12 +218,13 @@ private
 		# Si une expression est passée comme valeur initiale d'une
 		# variable, le type statique de la variable est implicitement
 		# celui de l'expression.
-		var s = "* Rayon : "
+		var s = new Buffer
+		s.append("* Rayon : ")
 		# Ici, le type statique de s est implicitement String
 
 		s.append(_rubrique)
 		s.add('\n')
-		return s
+		return s.to_s
 	end
 
 	meth cherche_produit(n: String): Produit
@@ -244,7 +245,8 @@ private
 
 	redef meth to_s: String
 	do
-		var s = to_s_head
+		var s = new Buffer
+		s.append(to_s_head)
 		# Les boucles en NIT sont des structures puissantes, toutefois
 		# la manipulation des itérateurs peut être facilité par la
 		# structure "for in"
@@ -261,7 +263,7 @@ private
 			s.append(p.to_s)
 			s.add('\n')
 		end
-		return s
+		return s.to_s
 	end
 
 
diff --git a/tests/example_point.nit b/tests/example_point.nit
index c2363c2..3ab94cb 100644
--- a/tests/example_point.nit
+++ b/tests/example_point.nit
@@ -47,11 +47,7 @@ private
 
 	redef meth to_s: String
 	do
-		var s = "("
-		s.append(_x.to_s)
-		s.add(':')
-		s.append(_y.to_s)
-		s.add(')')
+		var s = "({_x}:{_y})"
 		return s
 	end
 
diff --git a/tests/example_procedural_string.nit b/tests/example_procedural_string.nit
index 126fb85..35b7879 100644
--- a/tests/example_procedural_string.nit
+++ b/tests/example_procedural_string.nit
@@ -18,13 +18,13 @@
 
 meth first_word(s: String): String
 do
-	var result = new String
+	var result = new Buffer
 	var i = 0
 	while i < s.length and s[i] != ' ' do
 		result.add(s[i])
 		i = i + 1
 	end
-	return result
+	return result.to_s
 end
 
 print(first_word("Hello world!"))
diff --git a/tests/example_string.nit b/tests/example_string.nit
index 5371270..006efff 100644
--- a/tests/example_string.nit
+++ b/tests/example_string.nit
@@ -27,7 +27,7 @@ printn("The value of a is: ", a, ".\n")
 # Second way: Build a string and display it.
 # Pro: Eiffel way (rigourous).
 # Con: Eiffel way (heavy).
-var s = "The value of a is: "
+var s = new Buffer.from("The value of a is: ")
 s.append(a.to_s)
 s.append(".\n")
 printn(s)
diff --git a/tests/example_time.nit b/tests/example_time.nit
index ae694d6..9c47159 100644
--- a/tests/example_time.nit
+++ b/tests/example_time.nit
@@ -39,9 +39,7 @@ class Time
 	# The quantity of tyme in human readable form (h:m)
 	redef meth to_s: String
 	do
-		var s = hour.to_s		# Get the h
-		s.add(':')
-		s.append((_min % 60).to_s)	# Append the m
+		var s = "{hour}:{min%60}"
 		return s
 	end
 
diff --git a/tests/sav/test_symbol.sav b/tests/sav/test_symbol.sav
index 5ce0902..bc74ec5 100644
--- a/tests/sav/test_symbol.sav
+++ b/tests/sav/test_symbol.sav
@@ -3,7 +3,7 @@ TotoTataToto1
 false
 false
 true
-false
+true
 2
 false
 false
diff --git a/tests/shootout_nsieve.nit b/tests/shootout_nsieve.nit
index a9a3923..0e2542b 100644
--- a/tests/shootout_nsieve.nit
+++ b/tests/shootout_nsieve.nit
@@ -17,7 +17,7 @@
 meth nsieve(n: Int): Int
 do
 	var count = 0
-	var array = new String.with_capacity(n)
+	var array = new Buffer.with_capacity(n)
 	for i in [0..n[ do
 		array[i] = 'o'
 	end
diff --git a/tests/test_create_more.nit b/tests/test_create_more.nit
index 1b0fd1c..c1a0252 100644
--- a/tests/test_create_more.nit
+++ b/tests/test_create_more.nit
@@ -47,9 +47,9 @@ class A
 	do
 		var s = _num.to_s
 		if _attribute == null then
-			s.add('\n')
+			s += "\n"
 		else
-			s.append(_attribute.to_s)
+			s += _attribute.to_s
 		end
 		return s
 	end
diff --git a/tests/test_isa.nit b/tests/test_isa.nit
index 5b5ff3b..318a945 100644
--- a/tests/test_isa.nit
+++ b/tests/test_isa.nit
@@ -28,7 +28,7 @@ print("string:")
 a = "Bonjour"
 print(not a isa Int)
 print(a isa String)
-print(a isa AbstractArray[Char])
+print(a isa AbstractArrayRead[Char])
 print(not a isa Iterator[Int])
 print(not a isa Discrete)
 print(a isa Object)
diff --git a/tests/test_refinement.nit b/tests/test_refinement.nit
index 4f39f68..ad05e55 100644
--- a/tests/test_refinement.nit
+++ b/tests/test_refinement.nit
@@ -70,7 +70,7 @@ do
     print(a)
 end
 
-var b = "ab"
+var b = new Buffer.from("ab")
 do
     print(b)
     b.add('c')
diff --git a/tests/test_string_long.nit b/tests/test_string_long.nit
index 0429f07..94324a3 100644
--- a/tests/test_string_long.nit
+++ b/tests/test_string_long.nit
@@ -16,8 +16,8 @@
 
 
 var s = "Bonjour !\n"
-var r = new String.with_capacity(50)
-var r2 = ""
+var r = new Buffer.with_capacity(50)
+var r2 = new Buffer
 
 var i = 0
 while i < 5000 do
-- 
1.7.9.5