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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                                N A M E T                                 --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

with Alloc;

with Table;

with Hostparm; use Hostparm;

with System;   use System;

with Types;    use Types;

package Namet is

--  WARNING: There is a C version of this package. Any changes to this

--  source file must be properly reflected in the C header file namet.h

--  which is created manually from namet.ads and namet.adb.

--  This package contains routines for handling the names table. The table

--  is used to store character strings for identifiers and operator symbols,

--  as well as other string values such as unit names and file names.

--  The forms of the entries are as follows:

--    Identifiers Stored with upper case letters folded to lower case. Upper

--                       half (16#80# bit set) and wide characters are stored

--                       in an encoded form (Uhh for upper half char, Whhhh

--                       for wide characters, WWhhhhhhhh as provided by the

--                       routine Store_Encoded_Character, where hh are hex

--                       digits for the character code using lower case a-f).

--                       Normally the use of U or W in other internal names is

--                       avoided, but these letters may be used in internal

--                       names (without this special meaning), if they appear

--                       as the last character of the name, or they are

--                       followed by an upper case letter (other than the WW

--                       sequence), or an underscore.

--    Operator symbols   Stored with an initial letter O, and the remainder

--                       of the name is the lower case characters XXX where

--                       the name is Name_Op_XXX, see Snames spec for a full

--                       list of the operator names. Normally the use of O

--                       in other internal names is avoided, but it may be

--                       used in internal names (without this special meaning)

--                       if it is the last character of the name, or if it is

--                       followed by an upper case letter or an underscore.

--    Character literals Character literals have names that are used only for

--                       debugging and error message purposes. The form is a

--                       upper case Q followed by a single lower case letter,

--                       or by a Uxx/Wxxxx/WWxxxxxxx encoding as described for

--                       identifiers. The Set_Character_Literal_Name procedure

--                       should be used to construct these encodings. Normally

--                       the use of O in other internal names is avoided, but

--                       it may be used in internal names (without this special

--                       meaning) if it is the last character of the name, or

--                       if it is followed by an upper case letter or an

--                       underscore.

--    Unit names         Stored with upper case letters folded to lower case,

--                       using Uhh/Whhhh/WWhhhhhhhh encoding as described for

--                       identifiers, and a %s or %b suffix for specs/bodies.

--                       See package Uname for further details.

--    File names         Are stored in the form provided by Osint. Typically

--                       they may include wide character escape sequences and

--                       upper case characters (in non-encoded form). Casing

--                       is also derived from the external environment. Note

--                       that file names provided by Osint must generally be

--                       consistent with the names from Fname.Get_File_Name.

--    Other strings      The names table is also used as a convenient storage

--                       location for other variable length strings such as

--                       error messages etc. There are no restrictions on what

--                       characters may appear for such entries.

--  Note: the encodings Uhh (upper half characters), Whhhh (wide characters),

--  WWhhhhhhhh (wide wide characters) and Qx (character literal names) are

--  described in the spec, since they are visible throughout the system (e.g.

--  in debugging output). However, no code should depend on these particular

--  encodings, so it should be possible to change the encodings by making

--  changes only to the Namet specification (to change these comments) and the

--  body (which actually implements the encodings).

--  The names are hashed so that a given name appears only once in the table,

--  except that names entered with Name_Enter as opposed to Name_Find are

--  omitted from the hash table.

--  The first 26 entries in the names table (with Name_Id values in the range

--  First_Name_Id .. First_Name_Id + 25) represent names which are the one

--  character lower case letters in the range a-z, and these names are created

--  and initialized by the Initialize procedure.

--  Two values, one of type Int and one of type Byte, are stored with each

--  names table entry and subprograms are provided for setting and retrieving

--  these associated values. The usage of these values is up to the client. In

--  the compiler, the Int field is used to point to a chain of potentially

--  visible entities (see Sem.Ch8 for details), and the Byte field is used to

--  hold the Token_Type value for reserved words (see Sem for details). In the

--  binder, the Byte field is unused, and the Int field is used in various

--  ways depending on the name involved (see binder documentation).

   Name_Buffer : String (1 .. 4 * Max_Line_Length);

   --  This buffer is used to set the name to be stored in the table for the

   --  Name_Find call, and to retrieve the name for the Get_Name_String call.

   --  The limit here is intended to be an infinite value that ensures that we

   --  never overflow the buffer (names this long are too absurd to worry!)

   Name_Len : Natural;

   --  Length of name stored in Name_Buffer. Used as an input parameter for

   --  Name_Find, and as an output value by Get_Name_String, or Write_Name.

   -----------------------------

   -- Types for Namet Package --

   -----------------------------

   --  Name_Id values are used to identify entries in the names table. Except

   --  for the special values No_Name, and Error_Name, they are subscript

   --  values for the Names table defined in package Namet.

   --  Note that with only a few exceptions, which are clearly documented, the

   --  type Name_Id should be regarded as a private type. In particular it is

   --  never appropriate to perform arithmetic operations using this type.

   type Name_Id is range Names_Low_Bound .. Names_High_Bound;

   for Name_Id'Size use 32;

   --  Type used to identify entries in the names table

   No_Name : constant Name_Id := Names_Low_Bound;

   --  The special Name_Id value No_Name is used in the parser to indicate

   --  a situation where no name is present (e.g. on a loop or block).

   Error_Name : constant Name_Id := Names_Low_Bound +  1;

   --  The special Name_Id value Error_Name is used in the parser to

   --  indicate that some kind of error was encountered in scanning out

   --  the relevant name, so it does not have a representable label.

   subtype Error_Name_Or_No_Name is Name_Id range No_Name .. Error_Name;

   --  Used to test for either error name or no name

   First_Name_Id : constant Name_Id := Names_Low_Bound + 2;

   --  Subscript of first entry in names table

   -----------------

   -- Subprograms --

   -----------------

   procedure Finalize;

   --  Called at the end of a use of the Namet package (before a subsequent

   --  call to Initialize). Currently this routine is only used to generate

   --  debugging output.

   procedure Get_Name_String (Id : Name_Id);

   --  Get_Name_String is used to retrieve the string associated with an entry

   --  in the names table. The resulting string is stored in Name_Buffer and

   --  Name_Len is set. It is an error to call Get_Name_String with one of the

   --  special name Id values (No_Name or Error_Name).

   function Get_Name_String (Id : Name_Id) return String;

   --  This functional form returns the result as a string without affecting

   --  the contents of either Name_Buffer or Name_Len. The lower bound is 1.

   procedure Get_Unqualified_Name_String (Id : Name_Id);

   --  Similar to the above except that qualification (as defined in unit

   --  Exp_Dbug) is removed (including both preceding __ delimited names, and

   --  also the suffixes used to indicate package body entities and to

   --  distinguish between overloaded entities). Note that names are not

   --  qualified until just before the call to gigi, so this routine is only

   --  needed by processing that occurs after gigi has been called. This

   --  includes all ASIS processing, since ASIS works on the tree written

   --  after gigi has been called.

   procedure Get_Name_String_And_Append (Id : Name_Id);

   --  Like Get_Name_String but the resulting characters are appended to the

   --  current contents of the entry stored in Name_Buffer, and Name_Len is

   --  incremented to include the added characters.

   procedure Get_Decoded_Name_String (Id : Name_Id);

   --  Same calling sequence an interface as Get_Name_String, except that the

   --  result is decoded, so that upper half characters and wide characters

   --  appear as originally found in the source program text, operators have

   --  their source forms (special characters and enclosed in quotes), and

   --  character literals appear surrounded by apostrophes.

   procedure Get_Unqualified_Decoded_Name_String (Id : Name_Id);

   --  Similar to the above except that qualification (as defined in unit

   --  Exp_Dbug) is removed (including both preceding __ delimited names, and

   --  also the suffix used to indicate package body entities). Note that

   --  names are not qualified until just before the call to gigi, so this

   --  routine is only needed by processing that occurs after gigi has been

   --  called. This includes all ASIS processing, since ASIS works on the tree

   --  written after gigi has been called.

   procedure Get_Decoded_Name_String_With_Brackets (Id : Name_Id);

   --  This routine is similar to Decoded_Name, except that the brackets

   --  notation (Uhh replaced by ["hh"], Whhhh replaced by ["hhhh"],

   --  WWhhhhhhhh replaced by ["hhhhhhhh"]) is used for all non-lower half

   --  characters, regardless of how Opt.Wide_Character_Encoding_Method is

   --  set, and also in that characters in the range 16#80# .. 16#FF# are

   --  converted to brackets notation in all cases. This routine can be used

   --  when there is a requirement for a canonical representation not affected

   --  by the character set options (e.g. in the binder generation of

   --  symbols).

   function Get_Name_Table_Byte (Id : Name_Id) return Byte;

   pragma Inline (Get_Name_Table_Byte);

   --  Fetches the Byte value associated with the given name

   function Get_Name_Table_Info (Id : Name_Id) return Int;

   pragma Inline (Get_Name_Table_Info);

   --  Fetches the Int value associated with the given name

   function Is_Operator_Name (Id : Name_Id) return Boolean;

   --  Returns True if name given is of the form of an operator (that

   --  is, it starts with an upper case O).

   procedure Initialize;

   --  Initializes the names table, including initializing the first 26

   --  entries in the table (for the 1-character lower case names a-z) Note

   --  that Initialize must not be called if Tree_Read is used.

   procedure Lock;

   --  Lock name tables before calling back end. We reserve some extra space

   --  before locking to avoid unnecessary inefficiencies when we unlock.

   procedure Unlock;

   --  Unlocks the name table to allow use of the extra space reserved by the

   --  call to Lock. See gnat1drv for details of the need for this.

   function Length_Of_Name (Id : Name_Id) return Nat;

   pragma Inline (Length_Of_Name);

   --  Returns length of given name in characters. This is the length of the

   --  encoded name, as stored in the names table, the result is equivalent to

   --  calling Get_Name_String and reading Name_Len, except that a call to

   --  Length_Of_Name does not affect the contents of Name_Len and Name_Buffer.

   function Name_Chars_Address return System.Address;

   --  Return starting address of name characters table (used in Back_End call

   --  to Gigi).

   function Name_Find return Name_Id;

   --  Name_Find is called with a string stored in Name_Buffer whose length is

   --  in Name_Len (i.e. the characters of the name are in subscript positions

   --  1 to Name_Len in Name_Buffer). It searches the names table to see if

   --  the string has already been stored. If so the Id of the existing entry

   --  is returned. Otherwise a new entry is created with its Name_Table_Info

   --  field set to zero. The contents of Name_Buffer and Name_Len are not

   --  modified by this call. Note that it is permissible for Name_Len to be

   --  set to zero to lookup the null name string.

   function Name_Enter return Name_Id;

   --  Name_Enter has the same calling interface as Name_Find. The difference

   --  is that it does not search the table for an existing match, and also

   --  subsequent Name_Find calls using the same name will not locate the

   --  entry created by this call. Thus multiple calls to Name_Enter with the

   --  same name will create multiple entries in the name table with different

   --  Name_Id values. This is useful in the case of created names, which are

   --  never expected to be looked up. Note: Name_Enter should never be used

   --  for one character names, since these are efficiently located without

   --  hashing by Name_Find in any case.

   function Name_Entries_Address return System.Address;

   --  Return starting address of Names table (used in Back_End call to Gigi)

   function Name_Entries_Count return Nat;

   --  Return current number of entries in the names table

   function Is_OK_Internal_Letter (C : Character) return Boolean;

   pragma Inline (Is_OK_Internal_Letter);

   --  Returns true if C is a suitable character for using as a prefix or a

   --  suffix of an internally generated name, i.e. it is an upper case letter

   --  other than one of the ones used for encoding source names (currently

   --  the set of reserved letters is O, Q, U, W) and also returns False for

   --  the letter X, which is reserved for debug output (see Exp_Dbug).

   function Is_Internal_Name (Id : Name_Id) return Boolean;

   --  Returns True if the name is an internal name (i.e. contains a character

   --  for which Is_OK_Internal_Letter is true, or if the name starts or ends

   --  with an underscore. This call destroys the value of Name_Len and

   --  Name_Buffer (it loads these as for Get_Name_String).

   --

   --  Note: if the name is qualified (has a double underscore), then only the

   --  final entity name is considered, not the qualifying names. Consider for

   --  example that the name:

   --

   --    pkg__B_1__xyz

   --

   --  is not an internal name, because the B comes from the internal name of

   --  a qualifying block, but the xyz means that this was indeed a declared

   --  identifier called "xyz" within this block and there is nothing internal

   --  about that name.

   function Is_Internal_Name return Boolean;

   --  Like the form with an Id argument, except that the name to be tested is

   --  passed in Name_Buffer and Name_Len (which are not affected by the call).

   --  Name_Buffer (it loads these as for Get_Name_String).

   function Is_Valid_Name (Id : Name_Id) return Boolean;

   --  True if Id is a valid name -- points to a valid entry in the

   --  Name_Entries table.

   procedure Reset_Name_Table;

   --  This procedure is used when there are multiple source files to reset

   --  the name table info entries associated with current entries in the

   --  names table. There is no harm in keeping the names entries themselves

   --  from one compilation to another, but we can't keep the entity info,

   --  since this refers to tree nodes, which are destroyed between each main

   --  source file.

   procedure Add_Char_To_Name_Buffer (C : Character);

   pragma Inline (Add_Char_To_Name_Buffer);

   --  Add given character to the end of the string currently stored in the

   --  Name_Buffer, incrementing Name_Len.

   procedure Add_Nat_To_Name_Buffer (V : Nat);

   --  Add decimal representation of given value to the end of the string

   --  currently stored in Name_Buffer, incrementing Name_Len as required.

   procedure Add_Str_To_Name_Buffer (S : String);

   --  Add characters of string S to the end of the string currently stored

   --  in the Name_Buffer, incrementing Name_Len by the length of the string.

   procedure Set_Character_Literal_Name (C : Char_Code);

   --  This procedure sets the proper encoded name for the character literal

   --  for the given character code. On return Name_Buffer and Name_Len are

   --  set to reflect the stored name.

   procedure Set_Name_Table_Info (Id : Name_Id; Val : Int);

   pragma Inline (Set_Name_Table_Info);

   --  Sets the Int value associated with the given name

   procedure Set_Name_Table_Byte (Id : Name_Id; Val : Byte);

   pragma Inline (Set_Name_Table_Byte);

   --  Sets the Byte value associated with the given name

   procedure Store_Encoded_Character (C : Char_Code);

   --  Stores given character code at the end of Name_Buffer, updating the

   --  value in Name_Len appropriately. Lower case letters and digits are

   --  stored unchanged. Other 8-bit characters are stored using the Uhh

   --  encoding (hh = hex code), other 16-bit wide character values are stored

   --  using the Whhhh (hhhh = hex code) encoding, and other 32-bit wide wide

   --  character values are stored using the WWhhhhhhhh (hhhhhhhh = hex code).

   --  Note that this procedure does not fold upper case letters (they are

   --  stored using the Uhh encoding). If folding is required, it must be done

   --  by the caller prior to the call.

   procedure Tree_Read;

   --  Initializes internal tables from current tree file using the relevant

   --  Table.Tree_Read routines. Note that Initialize should not be called if

   --  Tree_Read is used. Tree_Read includes all necessary initialization.

   procedure Tree_Write;

   --  Writes out internal tables to current tree file using the relevant

   --  Table.Tree_Write routines.

   procedure Get_Last_Two_Chars (N : Name_Id; C1, C2 : out Character);

   --  Obtains last two characters of a name. C1 is last but one character

   --  and C2 is last character. If name is less than two characters long,

   --  then both C1 and C2 are set to ASCII.NUL on return.

   procedure Write_Name (Id : Name_Id);

   --  Write_Name writes the characters of the specified name using the

   --  standard output procedures in package Output. No end of line is

   --  written, just the characters of the name. On return Name_Buffer and

   --  Name_Len are set as for a call to Get_Name_String. The name is written

   --  in encoded form (i.e. including Uhh, Whhh, Qx, _op as they appear in

   --  the name table). If Id is Error_Name, or No_Name, no text is output.

   procedure Write_Name_Decoded (Id : Name_Id);

   --  Like Write_Name, except that the name written is the decoded name, as

   --  described for Get_Decoded_Name_String, and the resulting value stored

   --  in Name_Len and Name_Buffer is the decoded name.

   ------------------------------

   -- File and Unit Name Types --

   ------------------------------

   --  These are defined here in Namet rather than Fname and Uname to avoid

   --  problems with dependencies, and to avoid dragging in Fname and Uname

   --  into many more files, but it would be cleaner to move to Fname/Uname.

   type File_Name_Type is new Name_Id;

   --  File names are stored in the names table and this type is used to

   --  indicate that a Name_Id value is being used to hold a simple file name

   --  (which does not include any directory information).

   No_File : constant File_Name_Type := File_Name_Type (No_Name);

   --  Constant used to indicate no file is present (this is used for example

   --  when a search for a file indicates that no file of the name exists).

   Error_File_Name : constant File_Name_Type := File_Name_Type (Error_Name);

   --  The special File_Name_Type value Error_File_Name is used to indicate

   --  a unit name where some previous processing has found an error.

   subtype Error_File_Name_Or_No_File is

     File_Name_Type range No_File .. Error_File_Name;

   --  Used to test for either error file name or no file

   type Path_Name_Type is new Name_Id;

   --  Path names are stored in the names table and this type is used to

   --  indicate that a Name_Id value is being used to hold a path name (that

   --  may contain directory information).

   No_Path : constant Path_Name_Type := Path_Name_Type (No_Name);

   --  Constant used to indicate no path name is present

   type Unit_Name_Type is new Name_Id;

   --  Unit names are stored in the names table and this type is used to

   --  indicate that a Name_Id value is being used to hold a unit name, which

   --  terminates in %b for a body or %s for a spec.

   No_Unit_Name : constant Unit_Name_Type := Unit_Name_Type (No_Name);

   --  Constant used to indicate no file name present

   Error_Unit_Name : constant Unit_Name_Type := Unit_Name_Type (Error_Name);

   --  The special Unit_Name_Type value Error_Unit_Name is used to indicate

   --  a unit name where some previous processing has found an error.

   subtype Error_Unit_Name_Or_No_Unit_Name is

     Unit_Name_Type range No_Unit_Name .. Error_Unit_Name;

   ------------------------

   -- Debugging Routines --

   ------------------------

   procedure wn (Id : Name_Id);

   pragma Export (Ada, wn);

   --  This routine is intended for debugging use only (i.e. it is intended to

   --  be called from the debugger). It writes the characters of the specified

   --  name using the standard output procedures in package Output, followed by

   --  a new line. The name is written in encoded form (i.e. including Uhh,

   --  Whhh, Qx, _op as they appear in the name table). If Id is Error_Name,

   --  No_Name, or invalid an appropriate string is written (<Error_Name>,

   --  <No_Name>, <invalid name>). Unlike Write_Name, this call does not affect

   --  the contents of Name_Buffer or Name_Len.

   ---------------------------

   -- Table Data Structures --

   ---------------------------

   --  The following declarations define the data structures used to store

   --  names. The definitions are in the private part of the package spec,

   --  rather than the body, since they are referenced directly by gigi.

private

   --  This table stores the actual string names. Although logically there is

   --  no need for a terminating character (since the length is stored in the

   --  name entry table), we still store a NUL character at the end of every

   --  name (for convenience in interfacing to the C world).

   package Name_Chars is new Table.Table (

     Table_Component_Type => Character,

     Table_Index_Type     => Int,

     Table_Low_Bound      => 0,

     Table_Initial        => Alloc.Name_Chars_Initial,

     Table_Increment      => Alloc.Name_Chars_Increment,

     Table_Name           => "Name_Chars");

   type Name_Entry is record

      Name_Chars_Index : Int;

      --  Starting location of characters in the Name_Chars table minus one

      --  (i.e. pointer to character just before first character). The reason

      --  for the bias of one is that indexes in Name_Buffer are one's origin,

      --  so this avoids unnecessary adds and subtracts of 1.

      Name_Len : Short;

      --  Length of this name in characters

      Byte_Info : Byte;

      --  Byte value associated with this name

      Name_Has_No_Encodings : Boolean;

      --  This flag is set True if the name entry is known not to contain any

      --  special character encodings. This is used to speed up repeated calls

      --  to Get_Decoded_Name_String. A value of False means that it is not

      --  known whether the name contains any such encodings.

      Hash_Link : Name_Id;

      --  Link to next entry in names table for same hash code

      Int_Info : Int;

      --  Int Value associated with this name

   end record;

   for Name_Entry use record

      Name_Chars_Index      at  0 range 0 .. 31;

      Name_Len              at  4 range 0 .. 15;

      Byte_Info             at  6 range 0 .. 7;

      Name_Has_No_Encodings at  7 range 0 .. 7;

      Hash_Link             at  8 range 0 .. 31;

      Int_Info              at 12 range 0 .. 31;

   end record;

   for Name_Entry'Size use 16 * 8;

   --  This ensures that we did not leave out any fields

   --  This is the table that is referenced by Name_Id entries.

   --  It contains one entry for each unique name in the table.

   package Name_Entries is new Table.Table (

     Table_Component_Type => Name_Entry,

     Table_Index_Type     => Name_Id'Base,

     Table_Low_Bound      => First_Name_Id,

     Table_Initial        => Alloc.Names_Initial,

     Table_Increment      => Alloc.Names_Increment,

     Table_Name           => "Name_Entries");

end Namet;