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parser.cpp
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2000-01-07
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// $Id: parser.cpp,v 1.6 2000/01/07 00:25:53 lord Exp $
//
// This software is subject to the terms of the IBM Jikes Compiler
// License Agreement available at the following URL:
// http://www.ibm.com/research/jikes.
// Copyright (C) 1996, 1998, International Business Machines Corporation
// and others. All Rights Reserved.
// You must accept the terms of that agreement to use this software.
//
#include "config.h"
#include <assert.h>
#include <iostream.h>
#include "parser.h"
#include "ast.h"
void Parser::ReallocateStacks()
{
int old_stack_length = stack_length;
stack_length += STACK_INCREMENT;
assert(stack_length <= SHRT_MAX);
int *old_stack = stack;
stack = (int *) memmove(new int[stack_length], stack, old_stack_length * sizeof(int));
delete [] old_stack;
Location *old_location_stack = location_stack;
location_stack = (Location *) memmove(new Location[stack_length], location_stack, old_stack_length * sizeof(Location));
delete [] old_location_stack;
Ast **old_parse_stack = parse_stack;
parse_stack = (Ast **) memmove(new Ast *[stack_length], parse_stack, old_stack_length * sizeof(Ast *));
delete [] old_parse_stack;
parse_stack[old_stack_length] = NULL; // the first time through, we initialize parse_stack[0] to NULL !!!
int *old_temp_stack = temp_stack;
temp_stack = (int *) memmove(new int[stack_length], temp_stack, old_stack_length * sizeof(int));
delete [] old_temp_stack;
return;
}
AstListNode *Parser::AllocateListNode()
{
AstListNode *p;
if (free_list_nodes)
{
p = free_list_nodes;
free_list_nodes = free_list_nodes -> next;
}
else p = list_node_pool -> NewListNode();
return p;
}
void Parser::FreeCircularList(AstListNode *tail)
{
AstListNode *root = tail -> next;
tail -> next = free_list_nodes;
free_list_nodes = root;
return;
}
AstPackageDeclaration *Parser::PackageHeaderParse(LexStream *lex_stream_, StoragePool *ast_pool_)
{
AstPackageDeclaration *package_declaration = NULL;
lex_stream_ -> Reset();
if (lex_stream_ -> Kind(lex_stream_ -> Peek()) == TK_package)
{
ast_pool = ast_pool_;
parse_package_header_only = true;
end_token = LexStream::LEX_INFINITY; // We are parsing the whole input and not just a segment.
lex_stream = lex_stream_;
Ast *ast = HeaderParse();
parse_package_header_only = false;
if (ast)
{
AstCompilationUnit *compilation_unit = ast -> CompilationUnitCast();
if (compilation_unit && (! compilation_unit -> BadCompilationUnitCast()))
package_declaration = compilation_unit -> package_declaration_opt;
}
}
return package_declaration;
}
AstCompilationUnit *Parser::HeaderParse(LexStream *lex_stream_, StoragePool *ast_pool_)
{
lex_stream_ -> Reset();
body_pool = new StoragePool(lex_stream_ -> NumTokens());
ast_pool = (ast_pool_ ? ast_pool_ : body_pool);
list_node_pool = new StoragePool(lex_stream_ -> NumTokens());
free_list_nodes = NULL;
AstCompilationUnit *compilation_unit = NULL;
parse_header_only = true;
end_token = LexStream::LEX_INFINITY; // We are parsing the whole input and not just a segment.
lex_stream = lex_stream_;
Ast *ast = HeaderParse();
parse_header_only = false;
if (ast)
{
compilation_unit = ast -> CompilationUnitCast();
if (compilation_unit && (! compilation_unit -> BadCompilationUnitCast()))
{
if (compilation_unit -> NumTypeDeclarations() == 0)
compilation_unit -> kind = Ast::EMPTY_COMPILATION;
}
// STG:
// else delete ast;
//
}
//
// If we succesfully parsed a compilation unit, allocate a storage pool for it.
// Subtract the amount of space that's already been allocated for the headers
// from the estimate for the bodies.
//
if (compilation_unit)
compilation_unit -> ast_pool = body_pool;
else delete body_pool;
delete list_node_pool; // free the pool of list nodes
return compilation_unit;
}
Ast *Parser::HeaderParse()
{
TokenObject curtok = lex_stream -> Gettoken();
int act = START_STATE,
current_kind = lex_stream -> Kind(curtok);
/*****************************************************************/
/* Start parsing. */
/*****************************************************************/
state_stack_top = -1;
//
// Process a terminal
//
for (;;)
{
if (++state_stack_top >= stack_length)
ReallocateStacks();
stack[state_stack_top] = act;
location_stack[state_stack_top] = Loc(curtok);
act = t_action(act, current_kind, lex_stream);
if (act <= NUM_RULES)
state_stack_top--; // make reduction look like a shift-reduce
else if (act > ERROR_ACTION)
{
// STG:
// token_action(curtok);
curtok = lex_stream -> Gettoken();
current_kind = lex_stream -> Kind(curtok);
act -= ERROR_ACTION;
}
else if (act < ACCEPT_ACTION)
{
// STG:
// token_action(curtok);
curtok = lex_stream -> Gettoken();
current_kind = lex_stream -> Kind(curtok);
continue;
}
else break;
//
// Process a non_terminal
//
do
{
state_stack_top -= (rhs[act] - 1);
(this ->* rule_action[act])();
act = nt_action(stack[state_stack_top], lhs[act]);
} while(act <= NUM_RULES);
} /* process_terminal */
if (act == ERROR_ACTION)
{
//
// If any error is found in a package declaration, do not try to repair it.
//
if (! parse_package_header_only)
RepairParse(curtok);
if (parse_stack[0] && parse_stack[0] -> CompilationUnitCast())
parse_stack[0] -> kind = Ast::BAD_COMPILATION;
else
{
// STG:
// delete parse_stack[0];
parse_stack[0] = NULL;
}
}
return parse_stack[0];
}
bool Parser::BodyParse(LexStream *lex_stream_, AstClassBody *class_body)
{
assert(class_body -> UnparsedClassBodyCast());
lex_stream = lex_stream_;
ast_pool = class_body -> pool;
body_pool = class_body -> pool;
list_node_pool = new StoragePool(lex_stream_ -> NumTokens());
free_list_nodes = NULL;
bool no_errors_detected = Body(class_body);
delete list_node_pool; // free the pool of list nodes
class_body -> mark_parsed();
return no_errors_detected;
}
bool Parser::Body(AstClassBody *class_body)
{
bool no_errors_detected = true;
for (int i = 0; i < class_body -> NumConstructors(); i++)
{
AstConstructorDeclaration *constructor_decl = class_body -> Constructor(i);
if (constructor_decl -> constructor_symbol)
{
AstConstructorBlock *block = constructor_decl -> constructor_body;
end_token = block -> right_brace_token; // last token in the body
AstStatement *new_body = (AstStatement *) ParseSegment(block -> left_brace_token);
if (! new_body)
no_errors_detected = false;
else
{
AstConstructorBlock *new_block = new_body -> ConstructorBlockCast();
if (! new_block)
{
new_block = ast_pool -> GenConstructorBlock();
new_block -> left_brace_token = new_body -> LeftToken();
new_block -> explicit_constructor_invocation_opt = NULL;
new_block -> block = (AstBlock *) new_body;
new_block -> right_brace_token = new_body -> RightToken();
}
// STG:
// delete block; // destroy old empty block
//
constructor_decl -> constructor_body = new_block;
}
}
}
for (int j = 0; j < class_body -> NumMethods(); j++)
{
AstMethodDeclaration *method_decl = class_body -> Method(j);
if (method_decl -> method_symbol)
{
AstBlock *block = method_decl -> method_body -> BlockCast();
if (block)
{
end_token = block -> right_brace_token; // last token in the body
AstStatement *new_block = (AstStatement *) ParseSegment(block -> left_brace_token);
if (! new_block) // a bad block ?
no_errors_detected = false;
else
{
//
// The block associated with the method may syntactically be either a
// block or a constructor block. If it is a block, nest it inside the
// initial block. If it is a constructor block, replace the initial block
// by the constructor block.
//
if (new_block -> BlockCast())
block -> AddStatement(new_block);
else
{
method_decl -> method_body = new_block;
// STG:
// delete block; // destroy old empty block
}
}
}
}
}
for (int k = 0; k < class_body -> NumNestedClasses(); k++)
no_errors_detected = no_errors_detected && Body(class_body -> NestedClass(k) -> class_body);
for (int l = 0; l < class_body -> NumNestedInterfaces(); l++)
no_errors_detected = no_errors_detected && Body(class_body -> NestedInterface(l));
return no_errors_detected;
}
bool Parser::BodyParse(LexStream *lex_stream_, AstInterfaceDeclaration *interface_declaration)
{
assert(interface_declaration -> UnparsedInterfaceBodyCast());
lex_stream = lex_stream_;
ast_pool = interface_declaration -> pool;
body_pool = interface_declaration -> pool;
list_node_pool = new StoragePool(lex_stream_ -> NumTokens());
free_list_nodes = NULL;
bool no_errors_detected = Body(interface_declaration);
delete list_node_pool; // free the pool of list nodes
interface_declaration -> mark_parsed();
return no_errors_detected;
}
bool Parser::Body(AstInterfaceDeclaration *interface_declaration)
{
bool no_errors_detected = true;
for (int k = 0; k < interface_declaration -> NumNestedClasses(); k++)
no_errors_detected = no_errors_detected && Body(interface_declaration -> NestedClass(k) -> class_body);
for (int l = 0; l < interface_declaration -> NumNestedInterfaces(); l++)
no_errors_detected = no_errors_detected && Body(interface_declaration -> NestedInterface(l));
return no_errors_detected;
}
bool Parser::InitializerParse(LexStream *lex_stream_, AstClassBody *class_body)
{
lex_stream = lex_stream_;
ast_pool = class_body -> pool;
body_pool = class_body -> pool;
list_node_pool = new StoragePool(lex_stream_ -> NumTokens());
free_list_nodes = NULL;
bool no_errors_detected = Initializer(class_body);
delete list_node_pool; // free the pool of list nodes
return no_errors_detected;
}
bool Parser::InitializerParse(LexStream *lex_stream_, AstInterfaceDeclaration *interface_declaration)
{
lex_stream = lex_stream_;
ast_pool = interface_declaration -> pool;
body_pool = interface_declaration -> pool;
list_node_pool = new StoragePool(lex_stream_ -> NumTokens());
free_list_nodes = NULL;
bool no_errors_detected = Initializer(interface_declaration);
delete list_node_pool; // free the pool of list nodes
return no_errors_detected;
}
bool Parser::Initializer(AstClassBody *class_body)
{
bool no_errors_detected = true;
for (int i = 0; i < class_body -> NumStaticInitializers(); i++)
{
AstBlock *block = class_body -> StaticInitializer(i) -> block;
end_token = block -> right_brace_token; // last token in the body
class_body -> StaticInitializer(i) -> block = (AstBlock *) ParseSegment(block -> left_brace_token);
if (! class_body -> StaticInitializer(i) -> block)
{
no_errors_detected = false;
class_body -> StaticInitializer(i) -> block = block; // restore old empty block
}
// STG:
// else
// {
// delete block; // destroy old empty block
// }
}
for (int j = 0; j < class_body -> NumBlocks(); j++)
{
AstBlock *block = class_body -> Block(j);
end_token = block -> right_brace_token; // last token in the body
class_body -> Block(j) = (AstBlock *) ParseSegment(block -> left_brace_token);
if (! class_body -> Block(j))
{
no_errors_detected = false;
class_body -> Block(j) = block; // restore old empty block
}
//
// STG: if we ever go back to a new/free model of allocating Ast nodes
// This loop needs to be rewritten as otherwise, the new block allocated
// here would cause a memory leak since the class_body_declarations list
// is unaware of it. The solution is to iterate over the class_body_declarations
// list in order to locate the old block, free it and update the class_body_declarations
// list to point to the new block.
//
}
for (int k = 0; k < class_body -> NumNestedClasses(); k++)
no_errors_detected = no_errors_detected && Initializer(class_body -> NestedClass(k) -> class_body);
for (int l = 0; l < class_body -> NumNestedInterfaces(); l++)
no_errors_detected = no_errors_detected && Initializer(class_body -> NestedInterface(l));
return no_errors_detected;
}
bool Parser::Initializer(AstInterfaceDeclaration *interface_declaration)
{
bool no_errors_detected = true;
for (int k = 0; k < interface_declaration -> NumNestedClasses(); k++)
no_errors_detected = no_errors_detected && Initializer(interface_declaration -> NestedClass(k) -> class_body);
for (int l = 0; l < interface_declaration -> NumNestedInterfaces(); l++)
no_errors_detected = no_errors_detected && Initializer(interface_declaration -> NestedInterface(l));
return no_errors_detected;
}
Ast *Parser::ParseSegment(TokenObject start_token)
{
//
// The next call to Gettoken will return the start_token.
// However, we initialize curtok to start_token in order
// to obtain a valid location for the BodyMarker.
//
lex_stream -> Reset(start_token);
TokenObject curtok = start_token; // get the location of the start_token
int act = START_STATE,
current_kind = TK_BodyMarker;
/*****************************************************************/
/* Start parsing. */
/*****************************************************************/
state_stack_top = -1;
//
// Process a terminal
//
for (;;)
{
if (++state_stack_top >= stack_length)
ReallocateStacks();
stack[state_stack_top] = act;
location_stack[state_stack_top] = Loc(curtok);
act = t_action(act, current_kind, lex_stream);
if (act <= NUM_RULES)
state_stack_top--; // make reduction look like a shift-reduce
else if (act > ERROR_ACTION)
{
// STG:
// token_action(curtok);
curtok = lex_stream -> Gettoken(end_token);
current_kind = lex_stream -> Kind(curtok);
act -= ERROR_ACTION;
}
else if (act < ACCEPT_ACTION)
{
// STG:
// token_action(curtok);
curtok = lex_stream -> Gettoken(end_token);
current_kind = lex_stream -> Kind(curtok);
continue;
}
else break;
//
// Process a nonterminal
//
do
{
state_stack_top -= (rhs[act] - 1);
(this ->* rule_action[act])();
act = nt_action(stack[state_stack_top], lhs[act]);
} while(act <= NUM_RULES);
} /* process_terminal */
if (act == ERROR_ACTION)
{
RepairParse(curtok);
// STG:
// delete parse_stack[0];
parse_stack[0] = NULL;
}
return parse_stack[0];
}
void Parser::RepairParse(TokenObject curtok)
{
//
// Repair an error
//
for (;;)
{
//
// Pop state stack up to first state that had an
// action on the error token. The net effect is to
// remove all default reductions on an empty rule
// caused by the error token.
//
int k;
for (k = state_stack_top - 1; k >= 0 && location_stack[k] == Loc(curtok); k--)
;
k++;
// STG:
// for (int i = k; i < state_stack_top; i++)
// {
// delete parse_stack[i];
// }
state_stack_top = k;
ErrorRepair(curtok);
curtok = lex_stream -> Gettoken(end_token);
int act = stack[state_stack_top--];
int current_kind = lex_stream -> Kind(curtok);
//
// Process a terminal
//
for (;;)
{
if (++state_stack_top >= stack_length)
ReallocateStacks();
stack[state_stack_top] = act;
location_stack[state_stack_top] = Loc(curtok);
act = t_action(act, current_kind, lex_stream);
if (act <= NUM_RULES)
state_stack_top--; // make reduction look like a shift-reduce
else if (act > ERROR_ACTION)
{
// STG:
// token_action(curtok);
curtok = lex_stream -> Gettoken(end_token);
current_kind = lex_stream -> Kind(curtok);
act -= ERROR_ACTION;
}
else if (act < ACCEPT_ACTION)
{
// STG:
// token_action(curtok);
curtok = lex_stream -> Gettoken(end_token);
current_kind = lex_stream -> Kind(curtok);
continue;
}
//
// Since the null string is a valid Java program, this function
// will always succeed even if it has to delete the whole input.
//
else if (act == ACCEPT_ACTION)
return;
else break; // loop around and keep trying until something is accepted.
//
// Process a nonterminal
//
do
{
state_stack_top -= (rhs[act] - 1);
(this ->* rule_action[act])();
act = nt_action(stack[state_stack_top], lhs[act]);
} while(act <= NUM_RULES);
} /* process_terminal */
}
return;
}
//
// This routine is invoked when an error is encountered in a "repair"
// parser. It will place the parser back into a working configuration
// by adjusting the state stack, the current token and the buffer.
//
void Parser::ErrorRepair(TokenObject error_token)
{
SecondaryRepairInfo repair;
repair.code = 0;
do
{
repair.distance = 0;
repair.num_deletions = state_stack_top + BUFF_UBOUND;
buffer[1] = error_token;
buffer[0] = lex_stream -> Previous(buffer[1]);
for (int k = 2; k < BUFF_SIZE; k++)
buffer[k] = lex_stream -> Next(buffer[k - 1]);
int last_index;
for (last_index = MAX_DISTANCE - 1;
last_index >= 1 && lex_stream -> Kind(buffer[last_index]) == EOFT_SYMBOL;
last_index--);
last_index++;
repair = ErrorSurgery(stack, state_stack_top, last_index, repair);
error_token = buffer[MAX_DISTANCE - MIN_DISTANCE + 2];
} while (repair.code == 0);
// STG:
// for (int i = repair.stack_position; i < state_stack_top; i++)
// {
// delete parse_stack[i];
// }
state_stack_top = repair.stack_position;
lex_stream -> Reset(buffer[repair.buffer_position]);
return;
}
//
// Keep cutting "stuff" out around the error until a stable configuration
// is found.
//
SecondaryRepairInfo Parser::ErrorSurgery
(int stck[], int stack_top,
int last_index, SecondaryRepairInfo repair)
{
int stack_deletions = 0;
Location previous_loc = Loc(buffer[2]);
for (int top = stack_top; top >= 0 && repair.num_deletions >= stack_deletions; top--)
{
if (location_stack[top] < previous_loc)
stack_deletions++;
previous_loc = location_stack[top];
for (int i = 1; i <= last_index && repair.num_deletions >= (stack_deletions + i - 1); i++)
{
int j = ParseCheck(stck, top, lex_stream -> Kind(buffer[i]), i + 1);
if ((j - i + 1) > MIN_DISTANCE)
{
int k = stack_deletions + i - 1;
if ((k < repair.num_deletions) ||
(j - k) > (repair.distance - repair.num_deletions))
{
repair.code = DELETION_CODE;
repair.distance = j;
repair.stack_position = top;
repair.buffer_position = i;
repair.num_deletions = k;
}
}
}
}
return repair;
}
/*****************************************************************/
/* Try to parse until first_token and all tokens in BUFFER have */
/* been consumed, or an error is encountered. Return the number */
/* of tokens that were expended before the parse blocked. */
/*****************************************************************/
int Parser::ParseCheck(int stck[], int stack_top, int first_token, int buffer_position)
{
int max_pos,
indx,
ct,
act,
lhs_symbol;
/*****************************************************************/
/* Initialize pointer for temp_stack and initialize maximum */
/* position of state stack that is still useful. */
/*****************************************************************/
act = stck[stack_top];
if (first_token > NT_OFFSET)
{
temp_stack_top = stack_top;
max_pos = stack_top;
indx = buffer_position;
ct = lex_stream -> Kind(buffer[indx]);
lex_stream -> Reset(lex_stream -> Next(buffer[indx]));
lhs_symbol = first_token - NT_OFFSET;
act = nt_action(act, lhs_symbol);
if (act <= NUM_RULES)
goto process_non_terminal;
}
else
{
temp_stack_top = stack_top - 1;
max_pos = temp_stack_top;
indx = buffer_position - 1;
ct = first_token;
lex_stream -> Reset(buffer[buffer_position]);
}
process_terminal: for (;;)
{
if (++temp_stack_top >= stack_length) /* Stack overflow!!! */
return indx;
temp_stack[temp_stack_top] = act;
act = t_action(act, ct, lex_stream);
if (act <= NUM_RULES) /* reduce action */
temp_stack_top--;
else if (act < ACCEPT_ACTION || /* shift action */
act > ERROR_ACTION) /*shift-reduce action*/
{
if (indx == MAX_DISTANCE)
return indx;
indx++;
ct = lex_stream -> Kind(buffer[indx]);
lex_stream -> Reset(lex_stream -> Next(buffer[indx]));
if (act > ERROR_ACTION)
act -= ERROR_ACTION;
else goto process_terminal;
}
else if (act == ACCEPT_ACTION) /* accept action */
return MAX_DISTANCE;
else return indx; /* error action */
process_non_terminal:
do
{
temp_stack_top -= (rhs[act]-1);
lhs_symbol = lhs[act];
act = (temp_stack_top > max_pos
? temp_stack[temp_stack_top]
: stck[temp_stack_top]);
act = nt_action(act, lhs_symbol);
} while(act <= NUM_RULES);
max_pos = Min(max_pos, temp_stack_top);
} // process_terminal;
return 0;
}