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2012-04-26  Ed Schonberg  <schonberg@adacore.com>

	* gnat_ugn.texi: Tweak dimensionality doc.

2012-04-26  Robert Dewar  <dewar@adacore.com>

	* sem_eval.adb: Minor reformatting.

From-SVN: r186869
This commit is contained in:
Arnaud Charlet 2012-04-26 11:56:13 +02:00
parent 5f44f0d4f8
commit 7a6de2e28f
3 changed files with 24 additions and 7 deletions
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8
gcc/ada/ChangeLog
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@ -1,3 +1,11 @@
2012-04-26 Ed Schonberg <schonberg@adacore.com>
* gnat_ugn.texi: Tweak dimensionality doc.
2012-04-26 Robert Dewar <dewar@adacore.com>
* sem_eval.adb: Minor reformatting.
2012-04-26 Robert Dewar <dewar@adacore.com>
* einfo.adb, einfo.ads, sem_res.adb, sem_ch4.adb,

18
gcc/ada/gnat_ugn.texi
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@ -18534,6 +18534,10 @@ version 7.0.1 of GNAT onwards. The GNAT-specific aspect Dimension_System allows
the user to define a system of units; the aspect Dimension then allows the user
to declare dimensioned quantities within a given system.
The major advantage of this model is that it does not require the declaration of
multiple operators for all possible combinations of types: it is only necessary
to use the proper subtypes in object declarations.
The simplest way to impose dimensionality checking on a computation is to make
use of the package System.Dim.Mks, which is part of the GNAT library. This
package defines a floating-point type MKS_Type, for which a sequence of
@ -18592,11 +18596,12 @@ as well as useful multiples of these units:
@noindent
The user can then define a derived unit by providing the aspect that
specifies its dimensions within the MKS system:
specifies its dimensions within the MKS system, as well as the string to
be used for output of a value of that unit:
@smallexample @c ada
subtype Acceleration is Mks_Type
with Dimension => ("m/sec**2", 1, 0, -2, others => 0);
with Dimension => ("m/sec^^^2", Meter => 1, Second => -2, others => 0);
@end smallexample
@noindent
@ -18608,11 +18613,13 @@ with System.Dim.Mks_IO; use System.Dim.Mks_IO;
with Text_IO; use Text_IO;
procedure Free_Fall is
subtype Acceleration is Mks_Type
with Dimension => ("m/sec**2", 1, 0, -2, others => 0);
with Dimension => ("m/sec^^^2", 1, 0, -2, others => 0);
G : constant acceleration := 9.81 * m / (s ** 2);
T : Time := 10.0*s;
Distance : Length;
begin
Put ("Gravitational constant: ");
Put (G, Aft => 2, Exp => 0); Put_Line ("");
Distance := 0.5 * G * T ** 2;
Put ("distance travelled in 10 seconds of free fall ");
Put (Distance, Aft => 2, Exp => 0);
@ -18623,6 +18630,7 @@ end Free_Fall;
@noindent
Execution of this program yields:
@smallexample
Gravitational constant: 9.81 m/sec^^^2
distance travelled in 10 seconds of free fall 490.50 m
@end smallexample
@ -18650,8 +18658,8 @@ are rejected with the following diagnoses:
@end smallexample
@noindent
The dimensions of an expression are properly displayed. If we add to the
program:
The dimensions of an expression are properly displayed, even if there is
no explicit subtype for it. If we add to the program:
@smallexample @c ada
Put ("Final velocity: ");

5
gcc/ada/sem_eval.adb
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@ -516,6 +516,8 @@ package body Sem_Eval is
Subs : Nat;
begin
-- Fixup only required for First/Last attribute reference
if Nkind (N) = N_Attribute_Reference
and then (Attribute_Name (N) = Name_First
or else
@ -577,8 +579,7 @@ package body Sem_Eval is
if Attribute_Name (N) = Name_First then
return Type_Low_Bound (Xtyp);
else -- Attribute_Name (N) = Name_Last
else
return Type_High_Bound (Xtyp);
end if;
end if;