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

diff --git a/lib/standard/kernel.nit b/lib/standard/kernel.nit
index 80a1282..dfff892 100644
--- a/lib/standard/kernel.nit
+++ b/lib/standard/kernel.nit
@@ -11,8 +11,9 @@
 # You  are  allowed  to  redistribute it and sell it, alone or is a part of
 # another product.
 
+# Most minimal classes and methods.
 # This module is the root of the standard module hierarchy.
-package kernel
+module kernel
 
 import end # Mark this module is a top level one. (must be only one)
 
@@ -21,42 +22,101 @@ import end # Mark this module is a top level one. (must be only one)
 ###############################################################################
 
 # The root of the class hierarchy.
-# Each class implicitely specialize Object.
+# Each class implicitly specialize Object.
+#
+# Currently, Object is also used to collect all top-level methods.
 interface Object
-	# The unique object identifier in the class
-	meth object_id: Int is intern
-
-	# Return true is `self' and `other' have the same dynamic type
-	meth is_same_type(other: Object): Bool is intern
-
-	# Have `self' and `other' the same value?
-	##
-	# Implicitely, the default implementation, is ==
-	meth ==(other: nullable Object): Bool do return self is other
-
-	# Have `self' and `other' different values?
-	##
-	# != is equivament with "not =".
-	meth !=(other: nullable Object): Bool do return not (self == other)
+	# Type of this instance, automatically specialized in every class
+	#
+	# A common use case of the virtual type `SELF` is to type an attribute and
+	# store another instance of the same type as `self`. It can also be used as as
+	# return type to a method producing a copy of `self` or returning an instance
+	# expected to be the exact same type as self.
+	#
+	# This virtual type must be used with caution as it can hinder specialization.
+	# In fact, it imposes strict restrictions on all sub-classes and their usage.
+	# For example, using `SELF` as a return type of a method `foo`
+	# forces all subclasses to ensure that `foo` returns the correct and updated
+	# type.
+	# A dangerous usage take the form of a method typed by `SELF` which creates
+	# and returns a new instance.
+	# If not correctly specialized, this method would break when invoked on a
+	# sub-class.
+	#
+	# A general rule for safe usage of `SELF` is to ensure that inputs typed
+	# `SELF` are stored in attributes typed `SELF` and returned by methods typed
+	# `SELF`, pretty much the same things as you would do with parameter types.
+	type SELF: Object
+
+	# The unique object identifier in the class.
+	# Unless specific code, you should not use this method.
+	# The identifier is used internally to provide a hash value.
+	fun object_id: Int is intern
+
+	# Return true if `self` and `other` have the same dynamic type.
+	# Unless specific code, you should not use this method.
+	fun is_same_type(other: Object): Bool is intern
+
+	# Return true if `self` and `other` are the same instance.
+	# Unless specific code, you should use `==` instead.
+	fun is_same_instance(other: nullable Object): Bool is intern
+
+	# Have `self` and `other` the same value?
+	#
+	# The exact meaning of "same value" is let to the subclasses.
+	# Implicitly, the default implementation, is `is_same_instance`
+	fun ==(other: nullable Object): Bool do return self.is_same_instance(other)
+
+	# Have `self` and `other` different values?
+	#
+	# != is equivalent with "not ==".
+	fun !=(other: nullable Object): Bool do return not (self == other)
 
 	# Display self on stdout (debug only).
-	meth output
+	# This method MUST not be used by programs, it is here for debugging
+	# only and can be removed without any notice
+	fun output
 	do
 		'<'.output
 		object_id.output
 		'>'.output
 	end
 
-	protected meth exit(exit_value: Int) is intern # Quit the program.
-	protected meth sys: Sys is intern # The global sys object
+	# Display class name on stdout (debug only).
+	# This method MUST not be used by programs, it is here for debugging
+	# only and can be removed without any notice
+	fun output_class_name is intern	
+
+	# The hash code of the object.
+	# Assuming that a == b -> a.hash == b.hash
+	#
+	# Without redefinition, it is based on the `object_id` of the instance.
+	fun hash: Int do return object_id / 8
 end
 
 # The main class of the program.
+# `Sys` is a singleton class, its only instance is `sys` defined in `Object`.
+# `sys` is used to invoke methods on the program on the system.
 class Sys
-	# Instructions outside classes implicetely redefine this method.
-	meth main do end
+	# Instructions outside classes implicitly redefine this method.
+	fun main do end
+
+	# The entry point for the execution of the whole program.
+	# Its job is to call `main` but some modules may want to refine it
+	# and inject specific work before or after the main part.
+	fun run do main
+
+	# Number of the last error
+	fun errno: Int is extern "sys_errno"
 end
 
+# Quit the program with a specific return code
+fun exit(exit_value: Int) is intern
+
+# Return the global sys object, the only instance of the `Sys` class.
+fun sys: Sys is intern
+
+
 ###############################################################################
 # Abstract Classes                                                            #
 ###############################################################################
@@ -64,22 +124,26 @@ end
 # The ancestor of class where objects are in a total order.
 # In order to work, the method '<' has to be redefined.
 interface Comparable
+	# What `self` can be compared to?
 	type OTHER: Comparable
 
-	# Is `self' lesser than `other'
-	meth <(other: OTHER): Bool is abstract 
+	# Is `self` lesser than `other`?
+	fun <(other: OTHER): Bool is abstract 
 
-	# not `other' < `self'
-	meth <=(other: OTHER): Bool do return not other < self
+	# not `other` < `self`
+	# Note, the implementation must ensure that: `(x<=y) == (x<y or x==y)`
+	fun <=(other: OTHER): Bool do return not other < self
 
-	# not `self' < `other' 
-	meth >=(other: OTHER): Bool do return not self < other
+	# not `self` < `other`
+	# Note, the implementation must ensure that: `(x>=y) == (x>y or x==y)`
+	fun >=(other: OTHER): Bool do return not self < other
 
-	# `other' < `self'
-	meth >(other: OTHER): Bool do return other < self
+	# `other` < `self`
+	fun >(other: OTHER): Bool do return other < self
 
 	# -1 if <, +1 if > and 0 otherwise
-	meth <=>(other: OTHER): Int
+	# Note, the implementation must ensure that: (x<=>y == 0) == (x==y)
+	fun <=>(other: OTHER): Int
 	do
 		if self < other then
 			return -1
@@ -91,13 +155,13 @@ interface Comparable
 	end
 
 	# c <= self <= d
-	meth is_between(c: OTHER, d: OTHER): Bool
+	fun is_between(c: OTHER, d: OTHER): Bool
 	do
 		return c <= self and self <= d
 	end
 
-	# The maximum between `self' and `other' (prefers `self' if equals).
-	meth max(other: OTHER): OTHER
+	# The maximum between `self` and `other` (prefers `self` if equals).
+	fun max(other: OTHER): OTHER
 	do
 		if self < other then
 			return other
@@ -106,8 +170,8 @@ interface Comparable
 		end
 	end
 
-	# The minimum between `self' and `c' (prefer `self' if equals)
-	meth min(c: OTHER): OTHER
+	# The minimum between `self` and `c` (prefer `self` if equals)
+	fun min(c: OTHER): OTHER
 	do
 		if c < self then
 			return c
@@ -119,26 +183,21 @@ end
 
 # Discrete total orders.
 interface Discrete
-special Comparable
+	super Comparable
 
 	redef type OTHER: Discrete
 
 	# The next element.
-	meth succ: OTHER do return self + 1
+	fun successor(i: Int): OTHER is abstract
 
 	# The previous element.
-	meth prec: OTHER do return self - 1
-
-	# The `i' th successor element.
-	meth +(i: Int): OTHER is abstract
-
-	# The `i' th previous element.
-	meth -(i: Int): OTHER is abstract
+	fun predecessor(i: Int): OTHER is abstract
 
 	# The distance between self and d.
-	# 10.distance(15)	# --> 5
-	# 'Z'.distance('A')	# --> 25
-	meth distance(d: OTHER): Int
+	#
+	#     assert 10.distance(15)	     ==  5
+	#     assert 'Z'.distance('A')	     ==  25
+	fun distance(d: OTHER): Int
 	do
 		var cursor: OTHER
 		var stop: OTHER
@@ -154,79 +213,248 @@ special Comparable
 
 		var nb = 0
 		while cursor < stop do
-			cursor = cursor.succ
+			cursor = cursor.successor(1)
 			nb += 1
 		end
 		return nb
 	end
 end
 
+# Something that can be cloned
+#
+# This interface introduces the `clone` method used to duplicate an instance
+# Its specific semantic is let to the subclasses.
+interface Cloneable
+	# Duplicate `self`
+	#
+	# The specific semantic of this method is let to the subclasses;
+	# Especially, if (and how) attributes are cloned (depth vs. shallow).
+	#
+	# As a rule of thumb, the principle of least astonishment should
+	# be used to guide the semantic.
+	#
+	# Note that as the returned clone depends on the semantic,
+	# the `==` method, if redefined, should ensure the equality
+	# between an object and its clone.
+	fun clone: SELF is abstract
+end
+
+# A numeric value supporting mathematical operations
+interface Numeric
+	super Comparable
+
+	redef type OTHER: Numeric
+
+	# Addition of `self` with `i`
+	fun +(i: OTHER): OTHER is abstract
+
+	# Substraction of `i` from `self`
+	fun -(i: OTHER): OTHER is abstract
+
+	# Inverse of `self`
+	fun -: OTHER is abstract
+
+	# Multiplication of `self` with `i`
+	fun *(i: OTHER): OTHER is abstract
+
+	# Division of `self` with `i`
+	fun /(i: OTHER): OTHER is abstract
+
+	# The integer part of `self`.
+	#
+	#     assert (0.0).to_i      == 0
+	#     assert (0.9).to_i      == 0
+	#     assert (-0.9).to_i     == 0
+	#     assert (9.9).to_i      == 9
+	#     assert (-9.9).to_i     == -9
+	fun to_i: Int is abstract
+
+	# The float equivalent of `self`
+	#
+	#     assert 5.to_f         == 5.0
+	#     assert 5.to_f         != 5 # Float and Int are not equals
+	fun to_f: Float is abstract
+
+	# Is this the value of zero in its domain?
+	fun is_zero: Bool do return self == zero
+
+	# The value of zero in the domain of `self`
+	fun zero: OTHER is abstract
+
+	# The value of `val` in the domain of `self`
+	#
+	#     assert 1.0.value_of(2) == 2.0
+	#     assert 1.0.value_of(2.0) == 2.0
+	#     assert 1.value_of(2) == 2
+	#     assert 1.value_of(2.0) == 2
+	fun value_of(val: Numeric): OTHER is abstract
+end
+
 ###############################################################################
 # Native classes                                                              #
 ###############################################################################
 
-# Native booleans.
-# `true' and `false' are the only instances.
-# Boolean are manipulated trought three special operators:
-#	 `and', `or', `not'.
+# Native Booleans.
+# `true` and `false` are the only instances.
+#
+# Boolean are manipulated trough three special operators:
+# `and`, `or`, `not`.
+#
 # Booleans are mainly used by conditional statement and loops.
 universal Bool
-	redef meth object_id is intern
-	redef meth ==(b) is intern
-	redef meth !=(b) is intern
-	redef meth output is intern
+	redef fun object_id is intern
+	redef fun ==(b) is intern
+	redef fun !=(b) is intern
+	redef fun output is intern
+	redef fun hash do return to_i
+
+	# 1 if true and 0 if false
+	fun to_i: Int
+	do
+		if self then
+			return 1
+		else
+			return 0
+		end
+	end
 end
 
 # Native floating point numbers.
 # Corresponds to C float.
 universal Float
-	redef meth object_id is intern
-	redef meth output is intern
-
-	meth <=(i: Float): Bool is intern
-	meth <(i: Float): Bool is intern
-	meth >=(i: Float): Bool is intern
-	meth >(i: Float): Bool is intern
-	meth +(i: Float): Float is intern
-	meth -: Float is intern
-	meth -(i: Float): Float is intern
-	meth *(i: Float): Float is intern
-	meth /(i: Float): Float is intern
-	
-	# The integer part of `self'.
-	meth to_i: Int is intern
+	super Numeric
+
+	redef type OTHER: Float
+
+	redef fun object_id is intern
+	redef fun ==(i) is intern
+	redef fun !=(i) is intern
+	redef fun output is intern
+
+	redef fun <=(i): Bool is intern
+	redef fun <(i): Bool is intern
+	redef fun >=(i): Bool is intern
+	redef fun >(i): Bool is intern
+
+	redef fun +(i) is intern
+	redef fun - is intern
+	redef fun -(i) is intern
+	redef fun *(i) is intern
+	redef fun /(i) is intern
+
+	redef fun to_i is intern
+	redef fun to_f do return self
+
+	redef fun zero do return 0.0
+	redef fun value_of(val) do return val.to_f
+
+	redef fun <=>(other)
+	do
+		if self < other then
+			return -1
+		else if other < self then
+			return 1
+		else
+			return 0
+		end
+	end
+
+	redef fun is_between(c, d)
+	do
+		if self < c or d < self then
+			return false
+		else
+			return true
+		end
+	end
+
+	# Compare float numbers with a given precision.
+	#
+	# Because of the loss of precision in floating numbers,
+	# the `==` method is often not the best way to compare them.
+	#
+	# ~~~
+	# assert 0.01.is_approx(0.02, 0.1)   == true
+	# assert 0.01.is_approx(0.02, 0.001) == false
+	# ~~~
+	fun is_approx(other, precision: Float): Bool
+	do
+		assert precision >= 0.0
+		return self <= other + precision and self >= other - precision
+	end
+
+	redef fun max(other)
+	do
+		if self < other then
+			return other
+		else
+			return self
+		end
+	end
+
+	redef fun min(c)
+	do
+		if c < self then
+			return c
+		else
+			return self
+		end
+	end
 end
 
 # Native integer numbers.
 # Correspond to C int.
 universal Int
-special Discrete
+	super Discrete
+	super Numeric
+
 	redef type OTHER: Int
 
-	redef meth object_id is intern
-	redef meth ==(i) is intern
-	redef meth !=(i) is intern
-	redef meth output is intern
-
-	redef meth <=(i) is intern
-	redef meth <(i) is intern
-	redef meth >=(i) is intern
-	redef meth >(i) is intern
-	redef meth +(i) is intern
-	meth -: Int is intern
-	redef meth -(i) is intern
-	meth *(i: Int): Int is intern
-	meth /(i: Int): Int is intern
-	meth %(i: Int): Int is intern   
-	meth lshift(i: Int): Int is intern
-	meth rshift(i: Int): Int is intern   
-
-	# The float equivalent of `self'
-	meth to_f: Float is intern
-
-	redef meth succ is intern
-	redef meth prec is intern
-	redef meth distance(i)
+	redef fun successor(i) do return self + i
+	redef fun predecessor(i) do return self - i
+
+	redef fun object_id is intern
+	redef fun hash do return self
+	redef fun ==(i) is intern
+	redef fun !=(i) is intern
+	redef fun output is intern
+
+	redef fun <=(i) is intern
+	redef fun <(i) is intern
+	redef fun >=(i) is intern
+	redef fun >(i) is intern
+	redef fun +(i) is intern
+
+	redef fun - is intern
+	redef fun -(i) is intern
+	redef fun *(i) is intern
+	redef fun /(i) is intern
+
+	# Modulo of `self` with `i`.
+	#
+	# Finds the remainder of division of `self` by `i`.
+	#
+	#     assert 5 % 2			== 1
+	#     assert 10 % 2			== 0
+	fun %(i: Int): Int is intern
+
+	redef fun zero do return 0
+	redef fun value_of(val) do return val.to_i
+
+	# `i` bits shift fo the left (aka <<)
+	#
+	#     assert 5.lshift(1)    == 10
+	fun lshift(i: Int): Int is intern
+
+	# `i` bits shift fo the right (aka >>)
+	#
+	#     assert 5.rshift(1)    == 2
+	fun rshift(i: Int): Int is intern
+
+	redef fun to_i do return self
+	redef fun to_f is intern
+
+	redef fun distance(i)
 	do
 		var d = self - i
 		if d >= 0 then
@@ -235,8 +463,8 @@ special Discrete
 			return -d
 		end
 	end
-	
-	redef meth <=>(other)
+
+	redef fun <=>(other)
 	do
 		if self < other then
 			return -1
@@ -247,7 +475,7 @@ special Discrete
 		end
 	end
 
-	redef meth is_between(c, d)
+	redef fun is_between(c, d)
 	do
 		if self < c or d < self then 
 			return false
@@ -256,7 +484,7 @@ special Discrete
 		end
 	end
 
-	redef meth max(other)
+	redef fun max(other)
 	do
 		if self < other then
 			return other
@@ -265,7 +493,7 @@ special Discrete
 		end
 	end
 
-	redef meth min(c)
+	redef fun min(c)
 	do
 		if c < self then
 			return c
@@ -274,12 +502,19 @@ special Discrete
 		end
 	end
 
-	# The character whose ASCII value is `self'.
-	meth ascii: Char is intern
-
-	# Number of digits of an integer in base `b' plus one if negative)
-	meth digit_count(b: Int): Int
+	# The character whose ASCII value is `self`.
+	#
+	#     assert 65.ascii   == 'A'
+	#     assert 10.ascii   == '\n'
+	fun ascii: Char is intern
+
+	# Number of digits of an integer in base `b` (plus one if negative)
+	#
+	#     assert 123.digit_count(10) == 3
+	#     assert 123.digit_count(2) == 7 # 1111011 in binary
+	fun digit_count(b: Int): Int
 	do
+		if b == 10 then return digit_count_base_10
 		var d: Int # number of digits
 		var n: Int # current number
 		# Sign
@@ -295,15 +530,39 @@ special Discrete
 		# count digits
 		while n > 0 do
 			d += 1
-			n = n / b  	# euclidian division /		
+			n = n / b  	# euclidian division /
 		end
 		return d
 	end
 
+	# Optimized version for base 10
+	fun digit_count_base_10: Int
+	do
+		var val: Int
+		var result: Int
+		if self < 0 then
+			result = 2
+			val = -self
+		else
+			result = 1
+			val = self
+		end
+		loop
+			if val < 10 then return result
+			if val < 100 then return result+1
+			if val < 1000 then return result+2
+			if val < 10000 then return result+3
+			val = val / 10000
+			result += 4
+		end
+	end
+
 	# Return the corresponding digit character
-	# If 0 <= `self' <= 9, return the corresponding character.
-	# If 10 <= `self' <= 36, return the corresponding letter [a..z].
-	meth to_c: Char
+	# If 0 <= `self` <= 9, return the corresponding character.
+	#     assert 5.to_c    == '5'
+	# If 10 <= `self` <= 36, return the corresponding letter [a..z].
+	#     assert 15.to_c   == 'f'
+	fun to_c: Char
 	do
 		assert self >= 0 and self <= 36 # TODO plan for this
 		if self < 10 then
@@ -312,29 +571,45 @@ special Discrete
 			return (self + ('a'.ascii - 10)).ascii
 		end
 	end
+
+	# The absolute value of self
+	#
+	#     assert (-10).abs   == 10
+	#     assert 10.abs    == 10
+	#     assert 0.abs     == 0
+	fun abs: Int
+	do
+	    if self >= 0
+	    then
+	        return self
+	    else
+	        return -1 * self
+	    end
+	end
 end
 
 # Native characters.
 # Characters are denoted with simple quote.
-# eg. 'a' or '\n'.
+# eg. `'a'` or `'\n'`.
 universal Char
-special Discrete
+	super Discrete
 	redef type OTHER: Char
 
-	redef meth object_id is intern
-	redef meth ==(o) is intern
-	redef meth !=(o) is intern
-	redef meth output is intern
+	redef fun object_id is intern
+	redef fun hash do return ascii
+	redef fun ==(o) is intern
+	redef fun !=(o) is intern
+	redef fun output is intern
 
-	redef meth <=(i) is intern
-	redef meth <(i) is intern
-	redef meth >=(i) is intern
-	redef meth >(i) is intern
+	redef fun <=(i) is intern
+	redef fun <(i) is intern
+	redef fun >=(i) is intern
+	redef fun >(i) is intern
 
-	redef meth succ is intern
-	redef meth prec is intern
+	redef fun successor(i) is intern
+	redef fun predecessor(i) is intern
 
-	redef meth distance(c)
+	redef fun distance(c)
 	do
 		var d = self.ascii - c.ascii
 		if d >= 0 then
@@ -344,46 +619,122 @@ special Discrete
 		end
 	end
 
-	# If `self' is a digit then return this digit.
-	meth to_i: Int
+	# If `self` is a digit then return this digit else return -1.
+	#
+	#     assert '5'.to_i    == 5
+	fun to_i: Int
 	do
 
 		if self == '-' then
 			return -1
-		else if self >= '0' and self <= '9' then
+		else if is_digit then
 			return self.ascii - '0'.ascii
 		else
-			return self.to_lower.ascii - ('a'.ascii + 10)
+			return self.to_lower.ascii - 'a'.ascii + 10
 		end
 	end
 
 	# the ascii value of self
-	meth ascii: Int is intern
-
-	redef meth +(i) is intern
-	redef meth -(i) is intern
-
-	# Char to lower case
-	meth to_lower : Char
+	#
+	#     assert 'a'.ascii    == 97
+	#     assert '\n'.ascii   == 10
+	fun ascii: Int is intern
+
+	# Return the lower case version of self.
+	# If self is not a letter, then return self
+	#
+	#     assert 'A'.to_lower  == 'a'
+	#     assert 'a'.to_lower  == 'a'
+	#     assert '$'.to_lower  == '$'
+	fun to_lower: Char
 	do
-		if self >= 'A' and self <= 'Z' then
+		if is_upper then
 			return (ascii + ('a'.distance('A'))).ascii
 		else
 			return self
 		end
 	end
 
-	# Char to upper case
-	meth to_upper : Char
+	# Return the upper case version of self.
+	# If self is not a letter, then return self
+	#
+	#     assert 'a'.to_upper  == 'A'
+	#     assert 'A'.to_upper  == 'A'
+	#     assert '$'.to_upper  == '$'
+	fun to_upper: Char
 	do
-		if self >= 'a' and self <= 'z' then
+		if is_lower then
 			return (ascii - ('a'.distance('A'))).ascii
 		else
 			return self
 		end
 	end
+
+	# Is self a digit? (from '0' to '9')
+	#
+	#     assert '0'.is_digit   == true
+	#     assert '9'.is_digit   == true
+	#     assert 'a'.is_digit   == false
+	fun is_digit : Bool
+	do
+		return self >= '0' and self <= '9'
+	end
+
+	# Is self a lower case letter? (from 'a' to 'z')
+	#
+	#     assert 'a'.is_lower   == true
+	#     assert 'z'.is_lower   == true
+	#     assert 'A'.is_lower   == false
+	#     assert '$'.is_lower   == false
+	fun is_lower : Bool
+	do
+		return self >= 'a' and self <= 'z'
+	end
+
+	# Is self a upper case letter? (from 'A' to 'Z')
+	#
+	#     assert 'A'.is_upper   == true
+	#     assert 'A'.is_upper   == true
+	#     assert 'z'.is_upper   == false
+	#     assert '$'.is_upper   == false
+	fun is_upper : Bool
+	do
+		return self >= 'A' and self <= 'Z'
+	end
+
+	# Is self a letter? (from 'A' to 'Z' and 'a' to 'z')
+	#
+	#     assert 'A'.is_letter  == true
+	#     assert 'A'.is_letter  == true
+	#     assert 'z'.is_letter  == true
+	#     assert '$'.is_letter  == false
+	fun is_letter : Bool
+	do
+		return is_lower or is_upper
+	end
+
+	# Is self a whitespace character?
+	#
+	# These correspond to the "Other" and "Separator" groups of the Unicode.
+	#
+	# In the ASCII encoding, this is those <= to space (0x20) plus delete (0x7F).
+	#
+	#     assert 'A'.is_whitespace  == false
+	#     assert ','.is_whitespace  == false
+	#     assert ' '.is_whitespace  == true
+	#     assert '\t'.is_whitespace == true
+	fun is_whitespace: Bool
+	do
+		var i = ascii
+		return i <= 0x20 or i == 0x7F
+	end
 end
 
 # Pointer classes are used to manipulate extern C structures.
-universal Pointer
+extern class Pointer
+	# Is the address behind this Object at NULL?
+	fun address_is_null: Bool is extern "address_is_null"
+
+	# Free the memory pointed by this pointer
+	fun free is extern "free"
 end