+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- P A R --
--- --
--- B o d y --
--- --
--- $Revision: 1.3.10.1 $
--- --
--- Copyright (C) 1992-2001 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 2, 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. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
--- --
--- GNAT was originally developed by the GNAT team at New York University. --
--- Extensive contributions were provided by Ada Core Technologies Inc. --
--- --
-------------------------------------------------------------------------------
-
-with Atree; use Atree;
-with Casing; use Casing;
-with Csets; use Csets;
-with Debug; use Debug;
-with Elists; use Elists;
-with Errout; use Errout;
-with Fname; use Fname;
-with Lib; use Lib;
-with Namet; use Namet;
-with Nlists; use Nlists;
-with Nmake; use Nmake;
-with Opt; use Opt;
-with Output; use Output;
-with Scans; use Scans;
-with Scn; use Scn;
-with Sinput; use Sinput;
-with Sinput.L; use Sinput.L;
-with Sinfo; use Sinfo;
-with Snames; use Snames;
-with Style;
-with Table;
-
-function Par (Configuration_Pragmas : Boolean) return List_Id is
-
- Num_Library_Units : Natural := 0;
- -- Count number of units parsed (relevant only in syntax check only mode,
- -- since in semantics check mode only a single unit is permitted anyway)
-
- Unit_Node : Node_Id;
- -- Stores compilation unit node for current unit
-
- Save_Config_Switches : Config_Switches_Type;
- -- Variable used to save values of config switches while we parse the
- -- new unit, to be restored on exit for proper recursive behavior.
-
- Loop_Block_Count : Nat := 0;
- -- Counter used for constructing loop/block names (see the routine
- -- Par.Ch5.Get_Loop_Block_Name)
-
- --------------------
- -- Error Recovery --
- --------------------
-
- -- When an error is encountered, a call is made to one of the Error_Msg
- -- routines to record the error. If the syntax scan is not derailed by the
- -- error (e.g. a complaint that logical operators are inconsistent in an
- -- EXPRESSION), then control returns from the Error_Msg call, and the
- -- parse continues unimpeded.
-
- -- If on the other hand, the Error_Msg represents a situation from which
- -- the parser cannot recover locally, the exception Error_Resync is raised
- -- immediately after the call to Error_Msg. Handlers for Error_Resync
- -- are located at strategic points to resynchronize the parse. For example,
- -- when an error occurs in a statement, the handler skips to the next
- -- semicolon and continues the scan from there.
-
- -- Each parsing procedure contains a note with the heading "Error recovery"
- -- which shows if it can propagate the Error_Resync exception. In order
- -- not to propagate the exception, a procedure must either contain its own
- -- handler for this exception, or it must not call any other routines which
- -- propagate the exception.
-
- -- Note: the arrangement of Error_Resync handlers is such that it should
- -- never be possible to transfer control through a procedure which made
- -- an entry in the scope stack, invalidating the contents of the stack.
-
- Error_Resync : exception;
- -- Exception raised on error that is not handled locally, see above.
-
- Last_Resync_Point : Source_Ptr;
- -- The resynchronization routines in Par.Sync run a risk of getting
- -- stuck in an infinite loop if they do not skip a token, and the caller
- -- keeps repeating the same resync call. On the other hand, if they skip
- -- a token unconditionally, some recovery opportunities are missed. The
- -- variable Last_Resync_Point records the token location previously set
- -- by a Resync call, and if a subsequent Resync call occurs at the same
- -- location, then the Resync routine does guarantee to skip a token.
-
- --------------------------------------------
- -- Handling Semicolon Used in Place of IS --
- --------------------------------------------
-
- -- The following global variables are used in handling the error situation
- -- of using a semicolon in place of IS in a subprogram declaration as in:
-
- -- procedure X (Y : Integer);
- -- Q : Integer;
- -- begin
- -- ...
- -- end;
-
- -- The two contexts in which this can appear are at the outer level, and
- -- within a declarative region. At the outer level, we know something is
- -- wrong as soon as we see the Q (or begin, if there are no declarations),
- -- and we can immediately decide that the semicolon should have been IS.
-
- -- The situation in a declarative region is more complex. The declaration
- -- of Q could belong to the outer region, and we do not know that we have
- -- an error until we hit the begin. It is still not clear at this point
- -- from a syntactic point of view that something is wrong, because the
- -- begin could belong to the enclosing subprogram or package. However, we
- -- can incorporate a bit of semantic knowledge and note that the body of
- -- X is missing, so we definitely DO have an error. We diagnose this error
- -- as semicolon in place of IS on the subprogram line.
-
- -- There are two styles for this diagnostic. If the begin immediately
- -- follows the semicolon, then we can place a flag (IS expected) right
- -- on the semicolon. Otherwise we do not detect the error until we hit
- -- the begin which refers back to the line with the semicolon.
-
- -- To control the process in the second case, the following global
- -- variables are set to indicate that we have a subprogram declaration
- -- whose body is required and has not yet been found. The prefix SIS
- -- stands for "Subprogram IS" handling.
-
- SIS_Entry_Active : Boolean;
- -- Set True to indicate that an entry is active (i.e. that a subprogram
- -- declaration has been encountered, and no body for this subprogram has
- -- been encountered). The remaining fields are valid only if this is True.
-
- SIS_Labl : Node_Id;
- -- Subprogram designator
-
- SIS_Sloc : Source_Ptr;
- -- Source location of FUNCTION/PROCEDURE keyword
-
- SIS_Ecol : Column_Number;
- -- Column number of FUNCTION/PROCEDURE keyword
-
- SIS_Semicolon_Sloc : Source_Ptr;
- -- Source location of semicolon at end of subprogram declaration
-
- SIS_Declaration_Node : Node_Id;
- -- Pointer to tree node for subprogram declaration
-
- SIS_Missing_Semicolon_Message : Error_Msg_Id;
- -- Used to save message ID of missing semicolon message (which will be
- -- modified to missing IS if necessary). Set to No_Error_Msg in the
- -- normal (non-error) case.
-
- -- Five things can happen to an active SIS entry
-
- -- 1. If a BEGIN is encountered with an SIS entry active, then we have
- -- exactly the situation in which we know the body of the subprogram is
- -- missing. After posting an error message, we change the spec to a body,
- -- rechaining the declarations that intervened between the spec and BEGIN.
-
- -- 2. Another subprogram declaration or body is encountered. In this
- -- case the entry gets overwritten with the information for the new
- -- subprogram declaration. We don't catch some nested cases this way,
- -- but it doesn't seem worth the effort.
-
- -- 3. A nested declarative region (e.g. package declaration or package
- -- body) is encountered. The SIS active indication is reset at the start
- -- of such a nested region. Again, like case 2, this causes us to miss
- -- some nested cases, but it doesn't seen worth the effort to stack and
- -- unstack the SIS information. Maybe we will reconsider this if we ever
- -- get a complaint about a missed case :-)
-
- -- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively
- -- supplies the missing body. In this case we reset the entry.
-
- -- 5. We encounter the end of the declarative region without encoutering
- -- a BEGIN first. In this situation we simply reset the entry. We know
- -- that there is a missing body, but it seems more reasonable to let the
- -- later semantic checking discover this.
-
- --------------------------------------------
- -- Handling IS Used in Place of Semicolon --
- --------------------------------------------
-
- -- This is a somewhat trickier situation, and we can't catch it in all
- -- cases, but we do our best to detect common situations resulting from
- -- a "cut and paste" operation which forgets to change the IS to semicolon.
- -- Consider the following example:
-
- -- package body X is
- -- procedure A;
- -- procedure B is
- -- procedure C;
- -- ...
- -- procedure D is
- -- begin
- -- ...
- -- end;
- -- begin
- -- ...
- -- end;
-
- -- The trouble is that the section of text from PROCEDURE B through END;
- -- consitutes a valid procedure body, and the danger is that we find out
- -- far too late that something is wrong (indeed most compilers will behave
- -- uncomfortably on the above example).
-
- -- We have two approaches to helping to control this situation. First we
- -- make every attempt to avoid swallowing the last END; if we can be
- -- sure that some error will result from doing so. In particular, we won't
- -- accept the END; unless it is exactly correct (in particular it must not
- -- have incorrect name tokens), and we won't accept it if it is immediately
- -- followed by end of file, WITH or SEPARATE (all tokens that unmistakeably
- -- signal the start of a compilation unit, and which therefore allow us to
- -- reserve the END; for the outer level.) For more details on this aspect
- -- of the handling, see package Par.Endh.
-
- -- If we can avoid eating up the END; then the result in the absense of
- -- any additional steps would be to post a missing END referring back to
- -- the subprogram with the bogus IS. Similarly, if the enclosing package
- -- has no BEGIN, then the result is a missing BEGIN message, which again
- -- refers back to the subprogram header.
-
- -- Such an error message is not too bad (it's already a big improvement
- -- over what many parsers do), but it's not ideal, because the declarations
- -- following the IS have been absorbed into the wrong scope. In the above
- -- case, this could result for example in a bogus complaint that the body
- -- of D was missing from the package.
-
- -- To catch at least some of these cases, we take the following additional
- -- steps. First, a subprogram body is marked as having a suspicious IS if
- -- the declaration line is followed by a line which starts with a symbol
- -- that can start a declaration in the same column, or to the left of the
- -- column in which the FUNCTION or PROCEDURE starts (normal style is to
- -- indent any declarations which really belong a subprogram). If such a
- -- subprogram encounters a missing BEGIN or missing END, then we decide
- -- that the IS should have been a semicolon, and the subprogram body node
- -- is marked (by setting the Bad_Is_Detected flag true. Note that we do
- -- not do this for library level procedures, only for nested procedures,
- -- since for library level procedures, we must have a body.
-
- -- The processing for a declarative part checks to see if the last
- -- declaration scanned is marked in this way, and if it is, the tree
- -- is modified to reflect the IS being interpreted as a semicolon.
-
- ---------------------------------------------------
- -- Parser Type Definitions and Control Variables --
- ---------------------------------------------------
-
- -- The following variable and associated type declaration are used by the
- -- expression parsing routines to return more detailed information about
- -- the categorization of a parsed expression.
-
- type Expr_Form_Type is (
- EF_Simple_Name, -- Simple name, i.e. possibly qualified identifier
- EF_Name, -- Simple expression which could also be a name
- EF_Simple, -- Simple expression which is not call or name
- EF_Range_Attr, -- Range attribute reference
- EF_Non_Simple); -- Expression that is not a simple expression
-
- Expr_Form : Expr_Form_Type;
-
- -- The following type is used for calls to P_Subprogram, P_Package, P_Task,
- -- P_Protected to indicate which of several possibilities is acceptable.
-
- type Pf_Rec is record
- Spcn : Boolean; -- True if specification OK
- Decl : Boolean; -- True if declaration OK
- Gins : Boolean; -- True if generic instantiation OK
- Pbod : Boolean; -- True if proper body OK
- Rnam : Boolean; -- True if renaming declaration OK
- Stub : Boolean; -- True if body stub OK
- Fil1 : Boolean; -- Filler to fill to 8 bits
- Fil2 : Boolean; -- Filler to fill to 8 bits
- end record;
- pragma Pack (Pf_Rec);
-
- function T return Boolean renames True;
- function F return Boolean renames False;
-
- Pf_Decl_Gins_Pbod_Rnam_Stub : constant Pf_Rec :=
- Pf_Rec'(F, T, T, T, T, T, F, F);
- Pf_Decl : constant Pf_Rec :=
- Pf_Rec'(F, T, F, F, F, F, F, F);
- Pf_Decl_Gins_Pbod_Rnam : constant Pf_Rec :=
- Pf_Rec'(F, T, T, T, T, F, F, F);
- Pf_Decl_Pbod : constant Pf_Rec :=
- Pf_Rec'(F, T, F, T, F, F, F, F);
- Pf_Pbod : constant Pf_Rec :=
- Pf_Rec'(F, F, F, T, F, F, F, F);
- Pf_Spcn : constant Pf_Rec :=
- Pf_Rec'(T, F, F, F, F, F, F, F);
- -- The above are the only allowed values of Pf_Rec arguments
-
- type SS_Rec is record
- Eftm : Boolean; -- ELSIF can terminate sequence
- Eltm : Boolean; -- ELSE can terminate sequence
- Extm : Boolean; -- EXCEPTION can terminate sequence
- Ortm : Boolean; -- OR can terminate sequence
- Sreq : Boolean; -- at least one statement required
- Tatm : Boolean; -- THEN ABORT can terminate sequence
- Whtm : Boolean; -- WHEN can terminate sequence
- Unco : Boolean; -- Unconditional terminate after one statement
- end record;
- pragma Pack (SS_Rec);
-
- SS_Eftm_Eltm_Sreq : constant SS_Rec := SS_Rec'(T, T, F, F, T, F, F, F);
- SS_Eltm_Ortm_Tatm : constant SS_Rec := SS_Rec'(F, T, F, T, F, T, F, F);
- SS_Extm_Sreq : constant SS_Rec := SS_Rec'(F, F, T, F, T, F, F, F);
- SS_None : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, F);
- SS_Ortm_Sreq : constant SS_Rec := SS_Rec'(F, F, F, T, T, F, F, F);
- SS_Sreq : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, F, F);
- SS_Sreq_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, T, F);
- SS_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, T, F);
- SS_Unco : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, T);
-
- Label_List : Elist_Id;
- -- List of label nodes for labels appearing in the current compilation.
- -- Used by Par.Labl to construct the corresponding implicit declarations.
-
- -----------------
- -- Scope Table --
- -----------------
-
- -- The scope table, also referred to as the scope stack, is used to
- -- record the current scope context. It is organized as a stack, with
- -- inner nested entries corresponding to higher entries on the stack.
- -- An entry is made when the parser encounters the opening of a nested
- -- construct (such as a record, task, package etc.), and then package
- -- Par.Endh uses this stack to deal with END lines (including properly
- -- dealing with END nesting errors).
-
- type SS_End_Type is
- -- Type of end entry required for this scope. The last two entries are
- -- used only in the subprogram body case to mark the case of a suspicious
- -- IS, or a bad IS (i.e. suspicions confirmed by missing BEGIN or END).
- -- See separate section on dealing with IS used in place of semicolon.
- -- Note that for many purposes E_Name, E_Suspicious_Is and E_Bad_Is are
- -- treated the same (E_Suspicious_Is and E_Bad_Is are simply special cases
- -- of E_Name). They are placed at the end of the enumeration so that a
- -- test for >= E_Name catches all three cases efficiently.
-
- (E_Dummy, -- dummy entry at outer level
- E_Case, -- END CASE;
- E_If, -- END IF;
- E_Loop, -- END LOOP;
- E_Record, -- END RECORD;
- E_Select, -- END SELECT;
- E_Name, -- END [name];
- E_Suspicious_Is, -- END [name]; (case of suspicious IS)
- E_Bad_Is); -- END [name]; (case of bad IS)
-
- -- The following describes a single entry in the scope table
-
- type Scope_Table_Entry is record
- Etyp : SS_End_Type;
- -- Type of end entry, as per above description
-
- Lreq : Boolean;
- -- A flag indicating whether the label, if present, is required to
- -- appear on the end line. It is referenced only in the case of
- -- Etyp = E_Name or E_Suspicious_Is where the name may or may not be
- -- required (yes for labeled block, no in other cases). Note that for
- -- all cases except begin, the question of whether a label is required
- -- can be determined from the other fields (for loop, it is required if
- -- it is present, and for the other constructs it is never required or
- -- allowed).
-
- Ecol : Column_Number;
- -- Contains the absolute column number (with tabs expanded) of the
- -- the expected column of the end assuming normal Ada indentation
- -- usage. If the RM_Column_Check mode is set, this value is used for
- -- generating error messages about indentation. Otherwise it is used
- -- only to control heuristic error recovery actions.
-
- Labl : Node_Id;
- -- This field is used only for the LOOP and BEGIN cases, and is the
- -- Node_Id value of the label name. For all cases except child units,
- -- this value is an entity whose Chars field contains the name pointer
- -- that identifies the label uniquely. For the child unit case the Labl
- -- field references an N_Defining_Program_Unit_Name node for the name.
- -- For cases other than LOOP or BEGIN, the Label field is set to Error,
- -- indicating that it is an error to have a label on the end line.
- -- (this is really a misuse of Error since there is no Error ???)
-
- Decl : List_Id;
- -- Points to the list of declarations (i.e. the declarative part)
- -- associated with this construct. It is set only in the END [name]
- -- cases, and is set to No_List for all other cases which do not have a
- -- declarative unit associated with them. This is used for determining
- -- the proper location for implicit label declarations.
-
- Node : Node_Id;
- -- Empty except in the case of entries for IF and CASE statements,
- -- in which case it contains the N_If_Statement or N_Case_Statement
- -- node. This is used for setting the End_Span field.
-
- Sloc : Source_Ptr;
- -- Source location of the opening token of the construct. This is
- -- used to refer back to this line in error messages (such as missing
- -- or incorrect end lines). The Sloc field is not used, and is not set,
- -- if a label is present (the Labl field provides the text name of the
- -- label in this case, which is fine for error messages).
-
- S_Is : Source_Ptr;
- -- S_Is is relevant only if Etyp is set to E_Suspicious_Is or
- -- E_Bad_Is. It records the location of the IS that is considered
- -- to be suspicious.
-
- Junk : Boolean;
- -- A boolean flag that is set true if the opening entry is the dubious
- -- result of some prior error, e.g. a record entry where the record
- -- keyword was missing. It is used to suppress the issuing of a
- -- corresponding junk complaint about the end line (we do not want
- -- to complain about a missing end record when there was no record).
- end record;
-
- -- The following declares the scope table itself. The Last field is the
- -- stack pointer, so that Scope.Table (Scope.Last) is the top entry. The
- -- oldest entry, at Scope_Stack (0), is a dummy entry with Etyp set to
- -- E_Dummy, and the other fields undefined. This dummy entry ensures that
- -- Scope_Stack (Scope_Stack_Ptr).Etyp can always be tested, and that the
- -- scope stack pointer is always in range.
-
- package Scope is new Table.Table (
- Table_Component_Type => Scope_Table_Entry,
- Table_Index_Type => Int,
- Table_Low_Bound => 0,
- Table_Initial => 50,
- Table_Increment => 100,
- Table_Name => "Scope");
-
- ---------------------------------
- -- Parsing Routines by Chapter --
- ---------------------------------
-
- -- Uncommented declarations in this section simply parse the construct
- -- corresponding to their name, and return an ID value for the Node or
- -- List that is created.
-
- package Ch2 is
- function P_Identifier return Node_Id;
- function P_Pragma return Node_Id;
-
- function P_Pragmas_Opt return List_Id;
- -- This function scans for a sequence of pragmas in other than a
- -- declaration sequence or statement sequence context. All pragmas
- -- can appear except pragmas Assert and Debug, which are only allowed
- -- in a declaration or statement sequence context.
-
- procedure P_Pragmas_Misplaced;
- -- Skips misplaced pragmas with a complaint
-
- procedure P_Pragmas_Opt (List : List_Id);
- -- Parses optional pragmas and appends them to the List
- end Ch2;
-
- package Ch3 is
- Missing_Begin_Msg : Error_Msg_Id;
- -- This variable is set by a call to P_Declarative_Part. Normally it
- -- is set to No_Error_Msg, indicating that no special processing is
- -- required by the caller. The special case arises when a statement
- -- is found in the sequence of declarations. In this case the Id of
- -- the message issued ("declaration expected") is preserved in this
- -- variable, then the caller can change it to an appropriate missing
- -- begin message if indeed the BEGIN is missing.
-
- function P_Access_Definition return Node_Id;
- function P_Access_Type_Definition return Node_Id;
- function P_Array_Type_Definition return Node_Id;
- function P_Basic_Declarative_Items return List_Id;
- function P_Constraint_Opt return Node_Id;
- function P_Declarative_Part return List_Id;
- function P_Defining_Identifier return Node_Id;
- function P_Discrete_Choice_List return List_Id;
- function P_Discrete_Range return Node_Id;
- function P_Discrete_Subtype_Definition return Node_Id;
- function P_Known_Discriminant_Part_Opt return List_Id;
- function P_Signed_Integer_Type_Definition return Node_Id;
- function P_Range return Node_Id;
- function P_Range_Or_Subtype_Mark return Node_Id;
- function P_Range_Constraint return Node_Id;
- function P_Record_Definition return Node_Id;
- function P_Subtype_Indication return Node_Id;
- function P_Subtype_Mark return Node_Id;
- function P_Subtype_Mark_Resync return Node_Id;
- function P_Unknown_Discriminant_Part_Opt return Boolean;
-
- procedure P_Component_Items (Decls : List_Id);
- -- Scan out one or more component items and append them to the
- -- given list. Only scans out more than one declaration in the
- -- case where the source has a single declaration with multiple
- -- defining identifiers.
-
- function Init_Expr_Opt (P : Boolean := False) return Node_Id;
- -- If an initialization expression is present (:= expression), then
- -- it is scanned out and returned, otherwise Empty is returned if no
- -- initialization expression is present. This procedure also handles
- -- certain common error cases cleanly. The parameter P indicates if
- -- a right paren can follow the expression (default = no right paren
- -- allowed).
-
- procedure Skip_Declaration (S : List_Id);
- -- Used when scanning statements to skip past a mispaced declaration
- -- The declaration is scanned out and appended to the given list.
- -- Token is known to be a declaration token (in Token_Class_Declk)
- -- on entry, so there definition is a declaration to be scanned.
-
- function P_Subtype_Indication (Subtype_Mark : Node_Id) return Node_Id;
- -- This version of P_Subtype_Indication is called when the caller has
- -- already scanned out the subtype mark which is passed as a parameter.
-
- function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id;
- -- Parse a subtype mark attribute. The caller has already parsed the
- -- subtype mark, which is passed in as the argument, and has checked
- -- that the current token is apostrophe.
-
- end Ch3;
-
- package Ch4 is
- function P_Aggregate return Node_Id;
- function P_Expression return Node_Id;
- function P_Expression_No_Right_Paren return Node_Id;
- function P_Expression_Or_Range_Attribute return Node_Id;
- function P_Function_Name return Node_Id;
- function P_Name return Node_Id;
- function P_Qualified_Simple_Name return Node_Id;
- function P_Qualified_Simple_Name_Resync return Node_Id;
- function P_Simple_Expression return Node_Id;
- function P_Simple_Expression_Or_Range_Attribute return Node_Id;
-
- function P_Qualified_Expression
- (Subtype_Mark : Node_Id)
- return Node_Id;
- -- This routine scans out a qualified expression when the caller has
- -- already scanned out the name and apostrophe of the construct.
-
- end Ch4;
-
- package Ch5 is
-
- function P_Statement_Name (Name_Node : Node_Id) return Node_Id;
- -- Given a node representing a name (which is a call), converts it
- -- to the syntactically corresponding procedure call statement.
-
- function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id;
- -- The argument indicates the acceptable termination tokens.
- -- See body in Par.Ch5 for details of the use of this parameter.
-
- procedure Parse_Decls_Begin_End (Parent : Node_Id);
- -- Parses declarations and handled statement sequence, setting
- -- fields of Parent node appropriately.
-
- end Ch5;
-
- package Ch6 is
- function P_Designator return Node_Id;
- function P_Defining_Program_Unit_Name return Node_Id;
- function P_Formal_Part return List_Id;
- function P_Parameter_Profile return List_Id;
- function P_Return_Statement return Node_Id;
- function P_Subprogram_Specification return Node_Id;
-
- procedure P_Mode (Node : Node_Id);
- -- Sets In_Present and/or Out_Present flags in Node scanning past
- -- IN, OUT or IN OUT tokens in the source.
-
- function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id;
- -- Scans out any construct starting with either of the keywords
- -- PROCEDURE or FUNCTION. The parameter indicates which possible
- -- possible kinds of construct (body, spec, instantiation etc.)
- -- are permissible in the current context.
-
- end Ch6;
-
- package Ch7 is
- function P_Package (Pf_Flags : Pf_Rec) return Node_Id;
- -- Scans out any construct starting with the keyword PACKAGE. The
- -- parameter indicates which possible kinds of construct (body, spec,
- -- instantiation etc.) are permissible in the current context.
- end Ch7;
-
- package Ch8 is
- function P_Use_Clause return Node_Id;
- end Ch8;
-
- package Ch9 is
- function P_Abort_Statement return Node_Id;
- function P_Abortable_Part return Node_Id;
- function P_Accept_Statement return Node_Id;
- function P_Delay_Statement return Node_Id;
- function P_Entry_Body return Node_Id;
- function P_Protected return Node_Id;
- function P_Requeue_Statement return Node_Id;
- function P_Select_Statement return Node_Id;
- function P_Task return Node_Id;
- function P_Terminate_Alternative return Node_Id;
- end Ch9;
-
- package Ch10 is
- function P_Compilation_Unit return Node_Id;
- -- Note: this function scans a single compilation unit, and
- -- checks that an end of file follows this unit, diagnosing
- -- any unexpected input as an error, and then skipping it, so
- -- that Token is set to Tok_EOF on return. An exception is in
- -- syntax-only mode, where multiple compilation units are
- -- permitted. In this case, P_Compilation_Unit does not check
- -- for end of file and there may be more compilation units to
- -- scan. The caller can uniquely detect this situation by the
- -- fact that Token is not set to Tok_EOF on return.
- end Ch10;
-
- package Ch11 is
- function P_Handled_Sequence_Of_Statements return Node_Id;
- function P_Raise_Statement return Node_Id;
-
- function Parse_Exception_Handlers return List_Id;
- -- Parses the partial construct EXCEPTION followed by a list of
- -- exception handlers which appears in a number of productions,
- -- and returns the list of exception handlers.
-
- end Ch11;
-
- package Ch12 is
- function P_Generic return Node_Id;
- function P_Generic_Actual_Part_Opt return List_Id;
- end Ch12;
-
- package Ch13 is
- function P_Representation_Clause return Node_Id;
-
- function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id;
- -- Function to parse a code statement. The caller has scanned out
- -- the name to be used as the subtype mark (but has not checked that
- -- it is suitable for use as a subtype mark, i.e. is either an
- -- identifier or a selected component). The current token is an
- -- apostrophe and the following token is either a left paren or
- -- RANGE (the latter being an error to be caught by P_Code_Statement.
- end Ch13;
-
- -- Note: the parsing for annexe J features (i.e. obsolescent features)
- -- is found in the logical section where these features would be if
- -- they were not obsolescent. In particular:
-
- -- Delta constraint is parsed by P_Delta_Constraint (3.5.9)
- -- At clause is parsed by P_At_Clause (13.1)
- -- Mod clause is parsed by P_Mod_Clause (13.5.1)
-
- ------------------
- -- End Handling --
- ------------------
-
- -- Routines for handling end lines, including scope recovery
-
- package Endh is
-
- function Check_End return Boolean;
- -- Called when an end sequence is required. In the absence of an error
- -- situation, Token contains Tok_End on entry, but in a missing end
- -- case, this may not be the case. Pop_End_Context is used to determine
- -- the appropriate action to be taken. The returned result is True if
- -- an End sequence was encountered and False if no End sequence was
- -- present. This occurs if the END keyword encountered was determined
- -- to be improper and deleted (i.e. Pop_End_Context set End_Action to
- -- Skip_And_Reject). Note that the END sequence includes a semicolon,
- -- except in the case of END RECORD, where a semicolon follows the END
- -- RECORD, but is not part of the record type definition itself.
-
- procedure End_Skip;
- -- Skip past an end sequence. On entry Token contains Tok_End, and we
- -- we know that the end sequence is syntactically incorrect, and that
- -- an appropriate error message has already been posted. The mission
- -- is simply to position the scan pointer to be the best guess of the
- -- position after the end sequence. We do not issue any additional
- -- error messages while carrying this out.
-
- procedure End_Statements (Parent : Node_Id := Empty);
- -- Called when an end is required or expected to terminate a sequence
- -- of statements. The caller has already made an appropriate entry in
- -- the Scope.Table to describe the expected form of the end. This can
- -- only be used in cases where the only appropriate terminator is end.
- -- If Parent is non-empty, then if a correct END line is encountered,
- -- the End_Label field of Parent is set appropriately.
-
- end Endh;
-
- ------------------------------------
- -- Resynchronization After Errors --
- ------------------------------------
-
- -- These procedures are used to resynchronize after errors. Following an
- -- error which is not immediately locally recoverable, the exception
- -- Error_Resync is raised. The handler for Error_Resync typically calls
- -- one of these recovery procedures to resynchronize the source position
- -- to a point from which parsing can be restarted.
-
- -- Note: these procedures output an information message that tokens are
- -- being skipped, but this message is output only if the option for
- -- Multiple_Errors_Per_Line is set in Options.
-
- package Sync is
-
- procedure Resync_Choice;
- -- Used if an error occurs scanning a choice. The scan pointer is
- -- advanced to the next vertical bar, arrow, or semicolon, whichever
- -- comes first. We also quit if we encounter an end of file.
-
- procedure Resync_Expression;
- -- Used if an error is detected during the parsing of an expression.
- -- It skips past tokens until either a token which cannot be part of
- -- an expression is encountered (an expression terminator), or if a
- -- comma or right parenthesis or vertical bar is encountered at the
- -- current parenthesis level (a parenthesis level counter is maintained
- -- to carry out this test).
-
- procedure Resync_Past_Semicolon;
- -- Used if an error occurs while scanning a sequence of declarations.
- -- The scan pointer is positioned past the next semicolon and the scan
- -- resumes. The scan is also resumed on encountering a token which
- -- starts a declaration (but we make sure to skip at least one token
- -- in this case, to avoid getting stuck in a loop).
-
- procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then;
- -- Used if an error occurs while scanning a sequence of statements.
- -- The scan pointer is positioned past the next semicolon, or to the
- -- next occurrence of either then or loop, and the scan resumes.
-
- procedure Resync_To_When;
- -- Used when an error occurs scanning an entry index specification.
- -- The scan pointer is positioned to the next WHEN (or to IS or
- -- semicolon if either of these appear before WHEN, indicating
- -- another error has occurred).
-
- procedure Resync_Semicolon_List;
- -- Used if an error occurs while scanning a parenthesized list of items
- -- separated by semicolons. The scan pointer is advanced to the next
- -- semicolon or right parenthesis at the outer parenthesis level, or
- -- to the next is or RETURN keyword occurrence, whichever comes first.
-
- procedure Resync_Cunit;
- -- Synchronize to next token which could be the start of a compilation
- -- unit, or to the end of file token.
-
- end Sync;
-
- -------------------------
- -- Token Scan Routines --
- -------------------------
-
- -- Routines to check for expected tokens
-
- package Tchk is
-
- -- Procedures with names of the form T_xxx, where Tok_xxx is a token
- -- name, check that the current token matches the required token, and
- -- if so, scan past it. If not, an error is issued indicating that
- -- the required token is not present (xxx expected). In most cases, the
- -- scan pointer is not moved in the not-found case, but there are some
- -- exceptions to this, see for example T_Id, where the scan pointer is
- -- moved across a literal appearing where an identifier is expected.
-
- procedure T_Abort;
- procedure T_Arrow;
- procedure T_At;
- procedure T_Body;
- procedure T_Box;
- procedure T_Colon;
- procedure T_Colon_Equal;
- procedure T_Comma;
- procedure T_Dot_Dot;
- procedure T_For;
- procedure T_Greater_Greater;
- procedure T_Identifier;
- procedure T_In;
- procedure T_Is;
- procedure T_Left_Paren;
- procedure T_Loop;
- procedure T_Mod;
- procedure T_New;
- procedure T_Of;
- procedure T_Or;
- procedure T_Private;
- procedure T_Range;
- procedure T_Record;
- procedure T_Right_Paren;
- procedure T_Semicolon;
- procedure T_Then;
- procedure T_Type;
- procedure T_Use;
- procedure T_When;
- procedure T_With;
-
- -- Procedures have names of the form TF_xxx, where Tok_xxx is a token
- -- name check that the current token matches the required token, and
- -- if so, scan past it. If not, an error message is issued indicating
- -- that the required token is not present (xxx expected).
-
- -- If the missing token is at the end of the line, then control returns
- -- immediately after posting the message. If there are remaining tokens
- -- on the current line, a search is conducted to see if the token
- -- appears later on the current line, as follows:
-
- -- A call to Scan_Save is issued and a forward search for the token
- -- is carried out. If the token is found on the current line before a
- -- semicolon, then it is scanned out and the scan continues from that
- -- point. If not the scan is restored to the point where it was missing.
-
- procedure TF_Arrow;
- procedure TF_Is;
- procedure TF_Loop;
- procedure TF_Return;
- procedure TF_Semicolon;
- procedure TF_Then;
- procedure TF_Use;
-
- end Tchk;
-
- ----------------------
- -- Utility Routines --
- ----------------------
-
- package Util is
-
- function Bad_Spelling_Of (T : Token_Type) return Boolean;
- -- This function is called in an error situation. It checks if the
- -- current token is an identifier whose name is a plausible bad
- -- spelling of the given keyword token, and if so, issues an error
- -- message, sets Token from T, and returns True. Otherwise Token is
- -- unchanged, and False is returned.
-
- procedure Check_Bad_Layout;
- -- Check for bad indentation in RM checking mode. Used for statements
- -- and declarations. Checks if current token is at start of line and
- -- is exdented from the current expected end column, and if so an
- -- error message is generated.
-
- procedure Check_Misspelling_Of (T : Token_Type);
- pragma Inline (Check_Misspelling_Of);
- -- This is similar to the function above, except that it does not
- -- return a result. It is typically used in a situation where any
- -- identifier is an error, and it makes sense to simply convert it
- -- to the given token if it is a plausible misspelling of it.
-
- procedure Check_95_Keyword (Token_95, Next : Token_Type);
- -- This routine checks if the token after the current one matches the
- -- Next argument. If so, the scan is backed up to the current token
- -- and Token_Type is changed to Token_95 after issuing an appropriate
- -- error message ("(Ada 83) keyword xx cannot be used"). If not,
- -- the scan is backed up with Token_Type unchanged. This routine
- -- is used to deal with an attempt to use a 95 keyword in Ada 83
- -- mode. The caller has typically checked that the current token,
- -- an identifier, matches one of the 95 keywords.
-
- procedure Check_Simple_Expression (E : Node_Id);
- -- Given an expression E, that has just been scanned, so that Expr_Form
- -- is still set, outputs an error if E is a non-simple expression. E is
- -- not modified by this call.
-
- procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id);
- -- Like Check_Simple_Expression, except that the error message is only
- -- given when operating in Ada 83 mode, and includes "in Ada 83".
-
- function Check_Subtype_Mark (Mark : Node_Id) return Node_Id;
- -- Called to check that a node representing a name (or call) is
- -- suitable for a subtype mark, i.e, that it is an identifier or
- -- a selected component. If so, or if it is already Error, then
- -- it is returned unchanged. Otherwise an error message is issued
- -- and Error is returned.
-
- function Comma_Present return Boolean;
- -- Used in comma delimited lists to determine if a comma is present, or
- -- can reasonably be assumed to have been present (an error message is
- -- generated in the latter case). If True is returned, the scan has been
- -- positioned past the comma. If False is returned, the scan position
- -- is unchanged. Note that all comma-delimited lists are terminated by
- -- a right paren, so the only legitimate tokens when Comma_Present is
- -- called are right paren and comma. If some other token is found, then
- -- Comma_Present has the job of deciding whether it is better to pretend
- -- a comma was present, post a message for a missing comma and return
- -- True, or return False and let the caller diagnose the missing right
- -- parenthesis.
-
- procedure Discard_Junk_Node (N : Node_Id);
- procedure Discard_Junk_List (L : List_Id);
- pragma Inline (Discard_Junk_Node);
- pragma Inline (Discard_Junk_List);
- -- These procedures do nothing at all, their effect is simply to discard
- -- the argument. A typical use is to skip by some junk that is not
- -- expected in the current context.
-
- procedure Ignore (T : Token_Type);
- -- If current token matches T, then give an error message and skip
- -- past it, otherwise the call has no effect at all. T may be any
- -- reserved word token, or comma, left or right paren, or semicolon.
-
- function Is_Reserved_Identifier return Boolean;
- -- Test if current token is a reserved identifier. This test is based
- -- on the token being a keyword and being spelled in typical identifier
- -- style (i.e. starting with an upper case letter).
-
- procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type);
- -- Called when the previous token is an identifier (whose Token_Node
- -- value is given by Prev) to check if current token is an identifier
- -- that can be merged with the previous one adding an underscore. The
- -- merge is only attempted if the following token matches Nxt. If all
- -- conditions are met, an error message is issued, and the merge is
- -- carried out, modifying the Chars field of Prev.
-
- procedure No_Constraint;
- -- Called in a place where no constraint is allowed, but one might
- -- appear due to a common error (e.g. after the type mark in a procedure
- -- parameter. If a constraint is present, an error message is posted,
- -- and the constraint is scanned and discarded.
-
- function No_Right_Paren (Expr : Node_Id) return Node_Id;
- -- Function to check for no right paren at end of expression, returns
- -- its argument if no right paren, else flags paren and returns Error.
-
- procedure Push_Scope_Stack;
- pragma Inline (Push_Scope_Stack);
- -- Push a new entry onto the scope stack. Scope.Last (the stack pointer)
- -- is incremented. The Junk field is preinitialized to False. The caller
- -- is expected to fill in all remaining entries of the new new top stack
- -- entry at Scope.Table (Scope.Last).
-
- procedure Pop_Scope_Stack;
- -- Pop an entry off the top of the scope stack. Scope_Last (the scope
- -- table stack pointer) is decremented by one. It is a fatal error to
- -- try to pop off the dummy entry at the bottom of the stack (i.e.
- -- Scope.Last must be non-zero at the time of call).
-
- function Separate_Present return Boolean;
- -- Determines if the current token is either Tok_Separate, or an
- -- identifier that is a possible misspelling of "separate" followed
- -- by a semicolon. True is returned if so, otherwise False.
-
- procedure Signal_Bad_Attribute;
- -- The current token is an identifier that is supposed to be an
- -- attribute identifier but is not. This routine posts appropriate
- -- error messages, including a check for a near misspelling.
-
- function Token_Is_At_Start_Of_Line return Boolean;
- pragma Inline (Token_Is_At_Start_Of_Line);
- -- Determines if the current token is the first token on the line
-
- end Util;
-
- ---------------------------------------
- -- Specialized Syntax Check Routines --
- ---------------------------------------
-
- function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id;
- -- This function is passed a tree for a pragma that has been scanned out.
- -- The pragma is syntactically well formed according to the general syntax
- -- for pragmas and the pragma identifier is for one of the recognized
- -- pragmas. It performs specific syntactic checks for specific pragmas.
- -- The result is the input node if it is OK, or Error otherwise. The
- -- reason that this is separated out is to facilitate the addition
- -- of implementation defined pragmas. The second parameter records the
- -- location of the semicolon following the pragma (this is needed for
- -- correct processing of the List and Page pragmas). The returned value
- -- is a copy of Pragma_Node, or Error if an error is found.
-
- -------------------------
- -- Subsidiary Routines --
- -------------------------
-
- procedure Labl;
- -- This procedure creates implicit label declarations for all label that
- -- are declared in the current unit. Note that this could conceptually
- -- be done at the point where the labels are declared, but it is tricky
- -- to do it then, since the tree is not hooked up at the point where the
- -- label is declared (e.g. a sequence of statements is not yet attached
- -- to its containing scope at the point a label in the sequence is found)
-
- procedure Load;
- -- This procedure loads all subsidiary units that are required by this
- -- unit, including with'ed units, specs for bodies, and parents for child
- -- units. It does not load bodies for inlined procedures and generics,
- -- since we don't know till semantic analysis is complete what is needed.
-
- -----------
- -- Stubs --
- -----------
-
- -- The package bodies can see all routines defined in all other subpackages
-
- use Ch2;
- use Ch3;
- use Ch4;
- use Ch5;
- use Ch6;
- use Ch7;
- use Ch8;
- use Ch9;
- use Ch10;
- use Ch11;
- use Ch12;
- use Ch13;
-
- use Endh;
- use Tchk;
- use Sync;
- use Util;
-
- package body Ch2 is separate;
- package body Ch3 is separate;
- package body Ch4 is separate;
- package body Ch5 is separate;
- package body Ch6 is separate;
- package body Ch7 is separate;
- package body Ch8 is separate;
- package body Ch9 is separate;
- package body Ch10 is separate;
- package body Ch11 is separate;
- package body Ch12 is separate;
- package body Ch13 is separate;
-
- package body Endh is separate;
- package body Tchk is separate;
- package body Sync is separate;
- package body Util is separate;
-
- function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id
- is separate;
-
- procedure Labl is separate;
- procedure Load is separate;
-
- ---------
- -- Par --
- ---------
-
--- This function is the parse routine called at the outer level. It parses
--- the current compilation unit and adds implicit label declarations.
-
-begin
- -- Deal with configuration pragmas case first
-
- if Configuration_Pragmas then
- declare
- Ecount : constant Int := Errors_Detected;
- Pragmas : List_Id := Empty_List;
- P_Node : Node_Id;
-
- begin
- loop
- if Token = Tok_EOF then
- return Pragmas;
-
- elsif Token /= Tok_Pragma then
- Error_Msg_SC ("only pragmas allowed in configuration file");
- return Error_List;
-
- else
- P_Node := P_Pragma;
-
- if Errors_Detected > Ecount then
- return Error_List;
- end if;
-
- if Chars (P_Node) > Last_Configuration_Pragma_Name
- and then Chars (P_Node) /= Name_Source_Reference
- then
- Error_Msg_SC
- ("only configuration pragmas allowed " &
- "in configuration file");
- return Error_List;
- end if;
-
- Append (P_Node, Pragmas);
- end if;
- end loop;
- end;
-
- -- Normal case of compilation unit
-
- else
- Save_Opt_Config_Switches (Save_Config_Switches);
-
- -- Special processing for language defined units. For this purpose
- -- we do NOT consider the renamings in annex J as predefined. That
- -- allows users to compile their own versions of these files, and
- -- in particular, in the VMS implementation, the DEC versions can
- -- be substituted for the standard Ada 95 versions.
-
- if Is_Predefined_File_Name
- (Fname => File_Name (Current_Source_File),
- Renamings_Included => False)
- then
- Set_Opt_Config_Switches
- (Is_Internal_File_Name (File_Name (Current_Source_File)));
-
- -- If this is the main unit, disallow compilation unless the -gnatg
- -- (GNAT mode) switch is set (from a user point of view, the rule is
- -- that language defined units cannot be recompiled).
-
- -- However, an exception is s-rpc, and its children. We test this
- -- by looking at the character after the minus, the rule is that
- -- System.RPC and its children are the only children in System
- -- whose second level name can start with the letter r.
-
- Get_Name_String (File_Name (Current_Source_File));
-
- if (Name_Len < 3 or else Name_Buffer (1 .. 3) /= "s-r")
- and then Current_Source_Unit = Main_Unit
- and then not GNAT_Mode
- and then Operating_Mode = Generate_Code
- then
- Error_Msg_SC ("language defined units may not be recompiled");
- end if;
- end if;
-
- -- The following loop runs more than once only in syntax check mode
- -- where we allow multiple compilation units in the same file.
-
- loop
- Set_Opt_Config_Switches
- (Is_Internal_File_Name (File_Name (Current_Source_File)));
-
- -- Initialize scope table and other parser control variables
-
- Compiler_State := Parsing;
- Scope.Init;
- Scope.Increment_Last;
- Scope.Table (0).Etyp := E_Dummy;
- SIS_Entry_Active := False;
- Last_Resync_Point := No_Location;
-
- Label_List := New_Elmt_List;
- Unit_Node := P_Compilation_Unit;
-
- -- If we are not at an end of file, then this means that we are
- -- in syntax scan mode, and we can have another compilation unit,
- -- otherwise we will exit from the loop.
-
- exit when Token = Tok_EOF;
- Restore_Opt_Config_Switches (Save_Config_Switches);
- Set_Comes_From_Source_Default (False);
- end loop;
-
- -- Now that we have completely parsed the source file, we can
- -- complete the source file table entry.
-
- Complete_Source_File_Entry;
-
- -- An internal error check, the scope stack should now be empty
-
- pragma Assert (Scope.Last = 0);
-
- -- Remaining steps are to create implicit label declarations and to
- -- load required subsidiary sources. These steps are required only
- -- if we are doing semantic checking.
-
- if Operating_Mode /= Check_Syntax or else Debug_Flag_F then
- Par.Labl;
- Par.Load;
- end if;
-
- -- Restore settings of switches saved on entry
-
- Restore_Opt_Config_Switches (Save_Config_Switches);
- Set_Comes_From_Source_Default (False);
- return Empty_List;
- end if;
-
-end Par;
projects / msp430-gcc.git / blobdiff