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// statements.h -- Go frontend statements. -*- C++ -*-
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#ifndef GO_STATEMENTS_H
#define GO_STATEMENTS_H
#include "operator.h"
class Gogo;
class Traverse;
class Statement_inserter;
class Block;
class Function;
class Unnamed_label;
class Export_function_body;
class Import_function_body;
class Assignment_statement;
class Temporary_statement;
class Variable_declaration_statement;
class Expression_statement;
class Block_statement;
class Return_statement;
class Thunk_statement;
class Defer_statement;
class Goto_statement;
class Goto_unnamed_statement;
class Label_statement;
class Unnamed_label_statement;
class If_statement;
class For_statement;
class For_range_statement;
class Switch_statement;
class Type_switch_statement;
class Send_statement;
class Select_statement;
class Variable;
class Named_object;
class Label;
class Translate_context;
class Expression;
class Expression_list;
class Struct_type;
class Call_expression;
class Map_index_expression;
class Receive_expression;
class Case_clauses;
class Type_case_clauses;
class Select_clauses;
class Typed_identifier_list;
class Bexpression;
class Bstatement;
class Bvariable;
class Ast_dump_context;
// This class is used to traverse assignments made by a statement
// which makes assignments.
class Traverse_assignments
{
public:
Traverse_assignments()
{ }
virtual ~Traverse_assignments()
{ }
// This is called for a variable initialization.
virtual void
initialize_variable(Named_object*) = 0;
// This is called for each assignment made by the statement. PLHS
// points to the left hand side, and PRHS points to the right hand
// side. PRHS may be NULL if there is no associated expression, as
// in the bool set by a non-blocking receive.
virtual void
assignment(Expression** plhs, Expression** prhs) = 0;
// This is called for each expression which is not passed to the
// assignment function. This is used for some of the statements
// which assign two values, for which there is no expression which
// describes the value. For ++ and -- the value is passed to both
// the assignment method and the rhs method. IS_STORED is true if
// this value is being stored directly. It is false if the value is
// computed but not stored. IS_LOCAL is true if the value is being
// stored in a local variable or this is being called by a return
// statement.
virtual void
value(Expression**, bool is_stored, bool is_local) = 0;
};
// A single statement.
class Statement
{
public:
// The types of statements.
enum Statement_classification
{
STATEMENT_ERROR,
STATEMENT_VARIABLE_DECLARATION,
STATEMENT_TEMPORARY,
STATEMENT_ASSIGNMENT,
STATEMENT_EXPRESSION,
STATEMENT_BLOCK,
STATEMENT_GO,
STATEMENT_DEFER,
STATEMENT_RETURN,
STATEMENT_BREAK_OR_CONTINUE,
STATEMENT_GOTO,
STATEMENT_GOTO_UNNAMED,
STATEMENT_LABEL,
STATEMENT_UNNAMED_LABEL,
STATEMENT_IF,
STATEMENT_CONSTANT_SWITCH,
STATEMENT_SEND,
STATEMENT_SELECT,
// These statements types are created by the parser, but they
// disappear during the lowering pass.
STATEMENT_ASSIGNMENT_OPERATION,
STATEMENT_TUPLE_ASSIGNMENT,
STATEMENT_TUPLE_MAP_ASSIGNMENT,
STATEMENT_TUPLE_RECEIVE_ASSIGNMENT,
STATEMENT_TUPLE_TYPE_GUARD_ASSIGNMENT,
STATEMENT_INCDEC,
STATEMENT_FOR,
STATEMENT_FOR_RANGE,
STATEMENT_SWITCH,
STATEMENT_TYPE_SWITCH
};
Statement(Statement_classification, Location);
virtual ~Statement();
// Make a variable declaration.
static Statement*
make_variable_declaration(Named_object*);
// Make a statement which creates a temporary variable and
// initializes it to an expression. The block is used if the
// temporary variable has to be explicitly destroyed; the variable
// must still be added to the block. References to the temporary
// variable may be constructed using make_temporary_reference.
// Either the type or the initialization expression may be NULL, but
// not both.
static Temporary_statement*
make_temporary(Type*, Expression*, Location);
// Make an assignment statement.
static Assignment_statement*
make_assignment(Expression*, Expression*, Location);
// Make an assignment operation (+=, etc.).
static Statement*
make_assignment_operation(Operator, Expression*, Expression*,
Location);
// Make a tuple assignment statement.
static Statement*
make_tuple_assignment(Expression_list*, Expression_list*, Location);
// Make an assignment from a map index to a pair of variables.
static Statement*
make_tuple_map_assignment(Expression* val, Expression* present,
Expression*, Location);
// Make an assignment from a nonblocking receive to a pair of
// variables.
static Statement*
make_tuple_receive_assignment(Expression* val, Expression* closed,
Expression* channel, Location);
// Make an assignment from a type guard to a pair of variables.
static Statement*
make_tuple_type_guard_assignment(Expression* val, Expression* ok,
Expression* expr, Type* type,
Location);
// Make an expression statement from an Expression. IS_IGNORED is
// true if the value is being explicitly ignored, as in an
// assignment to _.
static Statement*
make_statement(Expression*, bool is_ignored);
// Make a block statement from a Block. This is an embedded list of
// statements which may also include variable definitions.
static Block_statement*
make_block_statement(Block*, Location);
// Make an increment statement.
static Statement*
make_inc_statement(Expression*);
// Make a decrement statement.
static Statement*
make_dec_statement(Expression*);
// Make a go statement.
static Statement*
make_go_statement(Call_expression* call, Location);
// Make a defer statement.
static Statement*
make_defer_statement(Call_expression* call, Location);
// Make a return statement.
static Return_statement*
make_return_statement(Expression_list*, Location);
// Make a statement that returns the result of a call expression.
// If the call does not return any results, this just returns the
// call expression as a statement, assuming that the function will
// end immediately afterward.
static Statement*
make_return_from_call(Call_expression*, Location);
// Make a break statement.
static Statement*
make_break_statement(Unnamed_label* label, Location);
// Make a continue statement.
static Statement*
make_continue_statement(Unnamed_label* label, Location);
// Make a goto statement.
static Statement*
make_goto_statement(Label* label, Location);
// Make a goto statement to an unnamed label.
static Statement*
make_goto_unnamed_statement(Unnamed_label* label, Location);
// Make a label statement--where the label is defined.
static Statement*
make_label_statement(Label* label, Location);
// Make an unnamed label statement--where the label is defined.
static Statement*
make_unnamed_label_statement(Unnamed_label* label);
// Make an if statement.
static Statement*
make_if_statement(Expression* cond, Block* then_block, Block* else_block,
Location);
// Make a switch statement.
static Switch_statement*
make_switch_statement(Expression* switch_val, Location);
// Make a type switch statement.
static Type_switch_statement*
make_type_switch_statement(const std::string&, Expression*, Location);
// Make a send statement.
static Send_statement*
make_send_statement(Expression* channel, Expression* val, Location);
// Make a select statement.
static Select_statement*
make_select_statement(Location);
// Make a for statement.
static For_statement*
make_for_statement(Block* init, Expression* cond, Block* post,
Location location);
// Make a for statement with a range clause.
static For_range_statement*
make_for_range_statement(Expression* index_var, Expression* value_var,
Expression* range, Location);
// Return the statement classification.
Statement_classification
classification() const
{ return this->classification_; }
// Get the statement location.
Location
location() const
{ return this->location_; }
// Traverse the tree.
int
traverse(Block*, size_t* index, Traverse*);
// Traverse the contents of this statement--the expressions and
// statements which it contains.
int
traverse_contents(Traverse*);
// If this statement assigns some values, it calls a function for
// each value to which this statement assigns a value, and returns
// true. If this statement does not assign any values, it returns
// false.
bool
traverse_assignments(Traverse_assignments* tassign);
// Lower a statement. This is called immediately after parsing to
// simplify statements for further processing. It returns the same
// Statement or a new one. FUNCTION is the function containing this
// statement. BLOCK is the block containing this statement.
// INSERTER can be used to insert new statements before this one.
Statement*
lower(Gogo* gogo, Named_object* function, Block* block,
Statement_inserter* inserter)
{ return this->do_lower(gogo, function, block, inserter); }
// Flatten a statement. This is called immediately after the order of
// evaluation rules are applied to statements. It returns the same
// Statement or a new one. FUNCTION is the function containing this
// statement. BLOCK is the block containing this statement.
// INSERTER can be used to insert new statements before this one.
Statement*
flatten(Gogo* gogo, Named_object* function, Block* block,
Statement_inserter* inserter)
{ return this->do_flatten(gogo, function, block, inserter); }
// Set type information for unnamed constants.
void
determine_types();
// Check types in a statement. This simply checks that any
// expressions used by the statement have the right type.
void
check_types(Gogo* gogo)
{ this->do_check_types(gogo); }
// Return the cost of this statement for inlining purposes.
int
inlining_cost()
{ return this->do_inlining_cost(); }
// Export data for this statement to BODY.
void
export_statement(Export_function_body* efb)
{ this->do_export_statement(efb); }
// Make implicit type conversions explicit.
void
add_conversions()
{ this->do_add_conversions(); }
// Read a statement from export data. The location should be used
// for the returned statement. Errors should be reported using the
// Import_function_body's location method.
static Statement*
import_statement(Import_function_body*, Location);
// Return whether this is a block statement.
bool
is_block_statement() const
{ return this->classification_ == STATEMENT_BLOCK; }
// If this is an assignment statement, return it. Otherwise return
// NULL.
Assignment_statement*
assignment_statement()
{
return this->convert<Assignment_statement, STATEMENT_ASSIGNMENT>();
}
// If this is an temporary statement, return it. Otherwise return
// NULL.
Temporary_statement*
temporary_statement()
{
return this->convert<Temporary_statement, STATEMENT_TEMPORARY>();
}
// If this is a variable declaration statement, return it.
// Otherwise return NULL.
Variable_declaration_statement*
variable_declaration_statement()
{
return this->convert<Variable_declaration_statement,
STATEMENT_VARIABLE_DECLARATION>();
}
// If this is an expression statement, return it. Otherwise return
// NULL.
Expression_statement*
expression_statement()
{
return this->convert<Expression_statement, STATEMENT_EXPRESSION>();
}
// If this is an block statement, return it. Otherwise return
// NULL.
Block_statement*
block_statement()
{ return this->convert<Block_statement, STATEMENT_BLOCK>(); }
// If this is a return statement, return it. Otherwise return NULL.
Return_statement*
return_statement()
{ return this->convert<Return_statement, STATEMENT_RETURN>(); }
// If this is a thunk statement (a go or defer statement), return
// it. Otherwise return NULL.
Thunk_statement*
thunk_statement();
// If this is a defer statement, return it. Otherwise return NULL.
Defer_statement*
defer_statement()
{ return this->convert<Defer_statement, STATEMENT_DEFER>(); }
// If this is a goto statement, return it. Otherwise return NULL.
Goto_statement*
goto_statement()
{ return this->convert<Goto_statement, STATEMENT_GOTO>(); }
// If this is a goto_unnamed statement, return it. Otherwise return NULL.
Goto_unnamed_statement*
goto_unnamed_statement()
{ return this->convert<Goto_unnamed_statement, STATEMENT_GOTO_UNNAMED>(); }
// If this is a label statement, return it. Otherwise return NULL.
Label_statement*
label_statement()
{ return this->convert<Label_statement, STATEMENT_LABEL>(); }
// If this is an unnamed_label statement, return it. Otherwise return NULL.
Unnamed_label_statement*
unnamed_label_statement()
{ return this->convert<Unnamed_label_statement, STATEMENT_UNNAMED_LABEL>(); }
// If this is an if statement, return it. Otherwise return NULL.
If_statement*
if_statement()
{ return this->convert<If_statement, STATEMENT_IF>(); }
// If this is a for statement, return it. Otherwise return NULL.
For_statement*
for_statement()
{ return this->convert<For_statement, STATEMENT_FOR>(); }
// If this is a for statement over a range clause, return it.
// Otherwise return NULL.
For_range_statement*
for_range_statement()
{ return this->convert<For_range_statement, STATEMENT_FOR_RANGE>(); }
// If this is a switch statement, return it. Otherwise return NULL.
Switch_statement*
switch_statement()
{ return this->convert<Switch_statement, STATEMENT_SWITCH>(); }
// If this is a type switch statement, return it. Otherwise return
// NULL.
Type_switch_statement*
type_switch_statement()
{ return this->convert<Type_switch_statement, STATEMENT_TYPE_SWITCH>(); }
// If this is a send statement, return it. Otherwise return NULL.
Send_statement*
send_statement()
{ return this->convert<Send_statement, STATEMENT_SEND>(); }
// If this is a select statement, return it. Otherwise return NULL.
Select_statement*
select_statement()
{ return this->convert<Select_statement, STATEMENT_SELECT>(); }
// Return true if this statement may fall through--if after
// executing this statement we may go on to execute the following
// statement, if any.
bool
may_fall_through() const
{ return this->do_may_fall_through(); }
// Convert the statement to the backend representation.
Bstatement*
get_backend(Translate_context*);
// Dump AST representation of a statement to a dump context.
void
dump_statement(Ast_dump_context*) const;
protected:
// Implemented by child class: traverse the tree.
virtual int
do_traverse(Traverse*) = 0;
// Implemented by child class: traverse assignments. Any statement
// which includes an assignment should implement this.
virtual bool
do_traverse_assignments(Traverse_assignments*)
{ return false; }
// Implemented by the child class: lower this statement to a simpler
// one.
virtual Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*)
{ return this; }
// Implemented by the child class: lower this statement to a simpler
// one.
virtual Statement*
do_flatten(Gogo*, Named_object*, Block*, Statement_inserter*)
{ return this; }
// Implemented by child class: set type information for unnamed
// constants. Any statement which includes an expression needs to
// implement this.
virtual void
do_determine_types()
{ }
// Implemented by child class: check types of expressions used in a
// statement.
virtual void
do_check_types(Gogo*)
{ }
// Implemented by child class: return the cost of this statement for
// inlining. The default cost is high, so we only need to define
// this method for statements that can be inlined.
virtual int
do_inlining_cost()
{ return 0x100000; }
// Implemented by child class: write export data for this statement
// to the string. This need only be implemented by classes that
// implement do_inlining_cost with a reasonable value.
virtual void
do_export_statement(Export_function_body*)
{ go_unreachable(); }
// Implemented by child class: return true if this statement may
// fall through.
virtual bool
do_may_fall_through() const
{ return true; }
// Implemented by child class: convert to backend representation.
virtual Bstatement*
do_get_backend(Translate_context*) = 0;
// Implemented by child class: dump ast representation.
virtual void
do_dump_statement(Ast_dump_context*) const = 0;
// Implemented by child class: make implicit conversions explicit.
virtual void
do_add_conversions()
{ }
// Traverse an expression in a statement.
int
traverse_expression(Traverse*, Expression**);
// Traverse an expression list in a statement. The Expression_list
// may be NULL.
int
traverse_expression_list(Traverse*, Expression_list*);
// Traverse a type in a statement.
int
traverse_type(Traverse*, Type*);
// For children to call when they detect that they are in error.
void
set_is_error();
// For children to call to report an error conveniently.
void
report_error(const char*);
// For children to return an error statement from lower().
static Statement*
make_error_statement(Location);
private:
// Convert to the desired statement classification, or return NULL.
// This is a controlled dynamic cast.
template<typename Statement_class, Statement_classification sc>
Statement_class*
convert()
{
return (this->classification_ == sc
? static_cast<Statement_class*>(this)
: NULL);
}
template<typename Statement_class, Statement_classification sc>
const Statement_class*
convert() const
{
return (this->classification_ == sc
? static_cast<const Statement_class*>(this)
: NULL);
}
// The statement classification.
Statement_classification classification_;
// The location in the input file of the start of this statement.
Location location_;
};
// An assignment statement.
class Assignment_statement : public Statement
{
public:
Assignment_statement(Expression* lhs, Expression* rhs,
Location location)
: Statement(STATEMENT_ASSIGNMENT, location),
lhs_(lhs), rhs_(rhs), omit_write_barrier_(false)
{ }
Expression*
lhs() const
{ return this->lhs_; }
Expression*
rhs() const
{ return this->rhs_; }
bool
omit_write_barrier() const
{ return this->omit_write_barrier_; }
void
set_omit_write_barrier()
{ this->omit_write_barrier_ = true; }
protected:
int
do_traverse(Traverse* traverse);
bool
do_traverse_assignments(Traverse_assignments*);
virtual Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
void
do_determine_types();
void
do_check_types(Gogo*);
int
do_inlining_cost()
{ return 1; }
void
do_export_statement(Export_function_body*);
Statement*
do_flatten(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
void
do_add_conversions();
private:
// Left hand side--the lvalue.
Expression* lhs_;
// Right hand side--the rvalue.
Expression* rhs_;
// True if we can omit a write barrier from this assignment.
bool omit_write_barrier_;
};
// A statement which creates and initializes a temporary variable.
class Temporary_statement : public Statement
{
public:
Temporary_statement(Type* type, Expression* init, Location location)
: Statement(STATEMENT_TEMPORARY, location),
type_(type), init_(init), bvariable_(NULL), is_address_taken_(false),
value_escapes_(false), assigned_(false), uses_(0)
{ }
// Return the type of the temporary variable.
Type*
type() const;
// Return the initializer if there is one.
Expression*
init() const
{ return this->init_; }
// Set the initializer.
void
set_init(Expression* expr)
{ this->init_ = expr; }
// Whether something takes the address of this temporary
// variable.
bool
is_address_taken()
{ return this->is_address_taken_; }
// Record that something takes the address of this temporary
// variable.
void
set_is_address_taken()
{ this->is_address_taken_ = true; }
// Whether the value escapes.
bool
value_escapes() const
{ return this->value_escapes_; }
// Record that the value escapes.
void
set_value_escapes()
{ this->value_escapes_ = true; }
// Whether this temporary variable is assigned (after initialization).
bool
assigned()
{ return this->assigned_; }
// Record that this temporary variable is assigned.
void
set_assigned()
{ this->assigned_ = true; }
// Number of uses of this temporary variable.
int
uses()
{ return this->uses_; }
// Add one use of this temporary variable.
void
add_use()
{ this->uses_++; }
// Return the temporary variable. This should not be called until
// after the statement itself has been converted.
Bvariable*
get_backend_variable(Translate_context*) const;
// Import the declaration of a temporary.
static Statement*
do_import(Import_function_body*, Location);
protected:
int
do_traverse(Traverse*);
bool
do_traverse_assignments(Traverse_assignments*);
void
do_determine_types();
void
do_check_types(Gogo*);
int
do_inlining_cost()
{ return 1; }
void
do_export_statement(Export_function_body*);
Statement*
do_flatten(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
void
do_add_conversions();
private:
// The type of the temporary variable.
Type* type_;
// The initial value of the temporary variable. This may be NULL.
Expression* init_;
// The backend representation of the temporary variable.
Bvariable* bvariable_;
// True if something takes the address of this temporary variable.
bool is_address_taken_;
// True if the value assigned to this temporary variable escapes.
// This is used for select statements.
bool value_escapes_;
// True if this temporary variable is assigned (after initialization).
bool assigned_;
// Number of uses of this temporary variable.
int uses_;
};
// A variable declaration. This marks the point in the code where a
// variable is declared. The Variable is also attached to a Block.
class Variable_declaration_statement : public Statement
{
public:
Variable_declaration_statement(Named_object* var);
// The variable being declared.
Named_object*
var()
{ return this->var_; }
// Import a variable declaration.
static Statement*
do_import(Import_function_body*, Location);
protected:
int
do_traverse(Traverse*);
bool
do_traverse_assignments(Traverse_assignments*);
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
int
do_inlining_cost()
{ return 1; }
void
do_export_statement(Export_function_body*);
Statement*
do_flatten(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
void
do_add_conversions();
private:
Named_object* var_;
};
// A return statement.
class Return_statement : public Statement
{
public:
Return_statement(Expression_list* vals, Location location)
: Statement(STATEMENT_RETURN, location),
vals_(vals), is_lowered_(false)
{ }
// The list of values being returned. This may be NULL.
const Expression_list*
vals() const
{ return this->vals_; }
protected:
int
do_traverse(Traverse* traverse)
{ return this->traverse_expression_list(traverse, this->vals_); }
bool
do_traverse_assignments(Traverse_assignments*);
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
bool
do_may_fall_through() const
{ return false; }
int
do_inlining_cost()
{ return 1; }
void
do_export_statement(Export_function_body*);
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
private:
// Return values. This may be NULL.
Expression_list* vals_;
// True if this statement has been lowered.
bool is_lowered_;
};
// An expression statement.
class Expression_statement : public Statement
{
public:
Expression_statement(Expression* expr, bool is_ignored);
Expression*
expr()
{ return this->expr_; }
protected:
int
do_traverse(Traverse* traverse)
{ return this->traverse_expression(traverse, &this->expr_); }
void
do_determine_types();
void
do_check_types(Gogo*);
bool
do_may_fall_through() const;
int
do_inlining_cost()
{ return 0; }
void
do_export_statement(Export_function_body*);
Bstatement*
do_get_backend(Translate_context* context);
void
do_dump_statement(Ast_dump_context*) const;
private:
Expression* expr_;
// Whether the value of this expression is being explicitly ignored.
bool is_ignored_;
};
// A block statement--a list of statements which may include variable
// definitions.
class Block_statement : public Statement
{
public:
Block_statement(Block* block, Location location)
: Statement(STATEMENT_BLOCK, location),
block_(block), is_lowered_for_statement_(false)
{ }
// Return the actual block.
Block*
block() const
{ return this->block_; }
void
set_is_lowered_for_statement()
{ this->is_lowered_for_statement_ = true; }
bool
is_lowered_for_statement()
{ return this->is_lowered_for_statement_; }
// Export a block for a block statement.
static void
export_block(Export_function_body*, Block*, bool is_lowered_for_statement);
// Import a block statement, returning the block.
// *IS_LOWERED_FOR_STATEMENT reports whether this block statement
// was lowered from a for statement.
static Block*
do_import(Import_function_body*, Location, bool* is_lowered_for_statement);
protected:
int
do_traverse(Traverse* traverse)
{ return this->block_->traverse(traverse); }
void
do_determine_types()
{ this->block_->determine_types(); }
int
do_inlining_cost()
{ return 0; }
void
do_export_statement(Export_function_body*);
bool
do_may_fall_through() const
{ return this->block_->may_fall_through(); }
Bstatement*
do_get_backend(Translate_context* context);
void
do_dump_statement(Ast_dump_context*) const;
private:
Block* block_;
// True if this block statement represents a lowered for statement.
bool is_lowered_for_statement_;
};
// A send statement.
class Send_statement : public Statement
{
public:
Send_statement(Expression* channel, Expression* val,
Location location)
: Statement(STATEMENT_SEND, location),
channel_(channel), val_(val)
{ }
Expression*
channel()
{ return this->channel_; }
Expression*
val()
{ return this->val_; }
protected:
int
do_traverse(Traverse* traverse);
void
do_determine_types();
void
do_check_types(Gogo*);
Statement*
do_flatten(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
void
do_add_conversions();
private:
// The channel on which to send the value.
Expression* channel_;
// The value to send.
Expression* val_;
};
// Select_clauses holds the clauses of a select statement. This is
// built by the parser.
class Select_clauses
{
public:
Select_clauses()
: clauses_()
{ }
// Add a new clause. IS_SEND is true if this is a send clause,
// false for a receive clause. For a send clause CHANNEL is the
// channel and VAL is the value to send. For a receive clause
// CHANNEL is the channel, VAL is either NULL or a Var_expression
// for the variable to set, and CLOSED is either NULL or a
// Var_expression to set to whether the channel is closed. If VAL
// is NULL, VAR may be a variable to be initialized with the
// received value, and CLOSEDVAR may be a variable to be initialized
// with whether the channel is closed. IS_DEFAULT is true if this
// is the default clause. STATEMENTS is the list of statements to
// execute.
void
add(bool is_send, Expression* channel, Expression* val, Expression* closed,
Named_object* var, Named_object* closedvar, bool is_default,
Block* statements, Location location)
{
this->clauses_.push_back(Select_clause(is_send, channel, val, closed, var,
closedvar, is_default, statements,
location));
}
size_t
size() const
{ return this->clauses_.size(); }
// Traverse the select clauses.
int
traverse(Traverse*);
// Lower statements.
void
lower(Gogo*, Named_object*, Block*, Temporary_statement*,
Temporary_statement*);
// Determine types.
void
determine_types();
// Check types.
void
check_types();
// Whether the select clauses may fall through to the statement
// which follows the overall select statement.
bool
may_fall_through() const;
// Convert to the backend representation.
Bstatement*
get_backend(Translate_context*, Temporary_statement* index,
Unnamed_label* break_label, Location);
// Dump AST representation.
void
dump_clauses(Ast_dump_context*) const;
// A single clause.
class Select_clause
{
public:
Select_clause()
: channel_(NULL), val_(NULL), closed_(NULL), var_(NULL),
closedvar_(NULL), statements_(NULL), is_send_(false),
is_default_(false)
{ }
Select_clause(bool is_send, Expression* channel, Expression* val,
Expression* closed, Named_object* var,
Named_object* closedvar, bool is_default, Block* statements,
Location location)
: channel_(channel), val_(val), closed_(closed), var_(var),
closedvar_(closedvar), statements_(statements), location_(location),
is_send_(is_send), is_default_(is_default), is_lowered_(false)
{ go_assert(is_default ? channel == NULL : channel != NULL); }
// Traverse the select clause.
int
traverse(Traverse*);
// Lower statements.
void
lower(Gogo*, Named_object*, Block*, Temporary_statement*, size_t,
Temporary_statement*);
// Determine types.
void
determine_types();
// Check types.
void
check_types();
// Return true if this is the default clause.
bool
is_default() const
{ return this->is_default_; }
// Return the channel. This will return NULL for the default
// clause.
Expression*
channel() const
{ return this->channel_; }
// Return true for a send, false for a receive.
bool
is_send() const
{
go_assert(!this->is_default_);
return this->is_send_;
}
// Return the value to send or the lvalue to receive into.
Expression*
val() const
{ return this->val_; }
// Return the lvalue to set to whether the channel is closed
// on a receive.
Expression*
closed() const
{ return this->closed_; }
// Return the variable to initialize, for "case a := <-ch".
Named_object*
var() const
{ return this->var_; }
// Return the variable to initialize to whether the channel
// is closed, for "case a, c := <-ch".
Named_object*
closedvar() const
{ return this->closedvar_; }
// Return the statements.
Block*
statements() const
{ return this->statements_; }
// Return the location.
Location
location() const
{ return this->location_; }
// Whether this clause may fall through to the statement which
// follows the overall select statement.
bool
may_fall_through() const;
// Convert the statements to the backend representation.
Bstatement*
get_statements_backend(Translate_context*);
// Dump AST representation.
void
dump_clause(Ast_dump_context*) const;
private:
// These values must match the values in libgo/go/runtime/select.go.
enum
{
caseRecv = 1,
caseSend = 2,
caseDefault = 3,
};
void
lower_default(Block*, Expression*);
void
lower_send(Block*, Expression*, Expression*);
void
lower_recv(Gogo*, Named_object*, Block*, Expression*, Expression*,
Temporary_statement*);
void
set_case(Block*, Expression*, Expression*, Expression*, int);
// The channel.
Expression* channel_;
// The value to send or the lvalue to receive into.
Expression* val_;
// The lvalue to set to whether the channel is closed on a
// receive.
Expression* closed_;
// The variable to initialize, for "case a := <-ch".
Named_object* var_;
// The variable to initialize to whether the channel is closed,
// for "case a, c := <-ch".
Named_object* closedvar_;
// The statements to execute.
Block* statements_;
// The location of this clause.
Location location_;
// Whether this is a send or a receive.
bool is_send_;
// Whether this is the default.
bool is_default_;
// Whether this has been lowered.
bool is_lowered_;
};
Select_clause&
at(size_t i)
{ return this->clauses_.at(i); }
private:
typedef std::vector<Select_clause> Clauses;
Clauses clauses_;
};
// A select statement.
class Select_statement : public Statement
{
public:
Select_statement(Location location)
: Statement(STATEMENT_SELECT, location),
clauses_(NULL), index_(NULL), break_label_(NULL), is_lowered_(false)
{ }
// Add the clauses.
void
add_clauses(Select_clauses* clauses)
{
go_assert(this->clauses_ == NULL);
this->clauses_ = clauses;
}
// Return the break label for this select statement.
Unnamed_label*
break_label();
protected:
int
do_traverse(Traverse* traverse)
{ return this->clauses_->traverse(traverse); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
void
do_determine_types()
{ this->clauses_->determine_types(); }
void
do_check_types(Gogo*)
{ this->clauses_->check_types(); }
bool
do_may_fall_through() const;
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
private:
// Lower a one-case select statement.
Statement*
lower_one_case(Block*);
// Lower a two-case select statement with one defualt case.
Statement*
lower_two_case(Block*);
// The select clauses.
Select_clauses* clauses_;
// A temporary that holds the index value returned by selectgo.
Temporary_statement* index_;
// The break label.
Unnamed_label* break_label_;
// Whether this statement has been lowered.
bool is_lowered_;
};
// A statement which requires a thunk: go or defer.
class Thunk_statement : public Statement
{
public:
Thunk_statement(Statement_classification, Call_expression*,
Location);
// Return the call expression.
Expression*
call() const
{ return this->call_; }
// Simplify a go or defer statement so that it only uses a single
// parameter.
bool
simplify_statement(Gogo*, Named_object*, Block*);
protected:
int
do_traverse(Traverse* traverse);
bool
do_traverse_assignments(Traverse_assignments*);
void
do_determine_types();
void
do_check_types(Gogo*);
// Return the function and argument for the call.
bool
get_fn_and_arg(Expression** pfn, Expression** parg);
private:
// Return whether this is a simple go statement.
bool
is_simple(Function_type*) const;
// Return whether the thunk function is a constant.
bool
is_constant_function() const;
// Build the struct to use for a complex case.
Struct_type*
build_struct(Function_type* fntype);
// Build the thunk.
void
build_thunk(Gogo*, const std::string&);
// Set the name to use for thunk field N.
void
thunk_field_param(int n, char* buf, size_t buflen);
// The function call to be executed in a separate thread (go) or
// later (defer).
Expression* call_;
// The type used for a struct to pass to a thunk, if this is not a
// simple call.
Struct_type* struct_type_;
};
// A go statement.
class Go_statement : public Thunk_statement
{
public:
Go_statement(Call_expression* call, Location location)
: Thunk_statement(STATEMENT_GO, call, location)
{ }
protected:
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
};
// A defer statement.
class Defer_statement : public Thunk_statement
{
public:
Defer_statement(Call_expression* call, Location location)
: Thunk_statement(STATEMENT_DEFER, call, location),
on_stack_(false)
{ }
void
set_on_stack()
{ this->on_stack_ = true; }
protected:
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
private:
static Type*
defer_struct_type();
bool on_stack_;
};
// A goto statement.
class Goto_statement : public Statement
{
public:
Goto_statement(Label* label, Location location)
: Statement(STATEMENT_GOTO, location),
label_(label)
{ }
// Return the label being jumped to.
Label*
label() const
{ return this->label_; }
// Import a goto statement.
static Statement*
do_import(Import_function_body*, Location);
protected:
int
do_traverse(Traverse*);
void
do_check_types(Gogo*);
bool
do_may_fall_through() const
{ return false; }
Bstatement*
do_get_backend(Translate_context*);
int
do_inlining_cost()
{ return 5; }
void
do_export_statement(Export_function_body*);
void
do_dump_statement(Ast_dump_context*) const;
private:
Label* label_;
};
// A goto statement to an unnamed label.
class Goto_unnamed_statement : public Statement
{
public:
Goto_unnamed_statement(Unnamed_label* label, Location location)
: Statement(STATEMENT_GOTO_UNNAMED, location),
label_(label)
{ }
Unnamed_label*
unnamed_label() const
{ return this->label_; }
protected:
int
do_traverse(Traverse*);
bool
do_may_fall_through() const
{ return false; }
Bstatement*
do_get_backend(Translate_context* context);
int
do_inlining_cost()
{ return 5; }
void
do_export_statement(Export_function_body*);
void
do_dump_statement(Ast_dump_context*) const;
private:
Unnamed_label* label_;
};
// A label statement.
class Label_statement : public Statement
{
public:
Label_statement(Label* label, Location location)
: Statement(STATEMENT_LABEL, location),
label_(label)
{ }
// Return the label itself.
Label*
label() const
{ return this->label_; }
// Import a label or unnamed label.
static Statement*
do_import(Import_function_body*, Location);
protected:
int
do_traverse(Traverse*);
Bstatement*
do_get_backend(Translate_context*);
int
do_inlining_cost()
{ return 1; }
void
do_export_statement(Export_function_body*);
void
do_dump_statement(Ast_dump_context*) const;
private:
// The label.
Label* label_;
};
// An unnamed label statement.
class Unnamed_label_statement : public Statement
{
public:
Unnamed_label_statement(Unnamed_label* label);
protected:
int
do_traverse(Traverse*);
Bstatement*
do_get_backend(Translate_context* context);
int
do_inlining_cost()
{ return 1; }
void
do_export_statement(Export_function_body*);
void
do_dump_statement(Ast_dump_context*) const;
private:
// The label.
Unnamed_label* label_;
};
// An if statement.
class If_statement : public Statement
{
public:
If_statement(Expression* cond, Block* then_block, Block* else_block,
Location location)
: Statement(STATEMENT_IF, location),
cond_(cond), then_block_(then_block), else_block_(else_block)
{ }
Expression*
condition() const
{ return this->cond_; }
Block*
then_block() const
{ return this->then_block_; }
Block*
else_block() const
{ return this->else_block_; }
// Import an if statement.
static Statement*
do_import(Import_function_body*, Location);
protected:
int
do_traverse(Traverse*);
void
do_determine_types();
void
do_check_types(Gogo*);
int
do_inlining_cost()
{ return 5; }
void
do_export_statement(Export_function_body*);
bool
do_may_fall_through() const;
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
private:
Expression* cond_;
Block* then_block_;
Block* else_block_;
};
// A for statement.
class For_statement : public Statement
{
public:
For_statement(Block* init, Expression* cond, Block* post,
Location location)
: Statement(STATEMENT_FOR, location),
init_(init), cond_(cond), post_(post), statements_(NULL),
break_label_(NULL), continue_label_(NULL)
{ }
// Add the statements.
void
add_statements(Block* statements)
{
go_assert(this->statements_ == NULL);
this->statements_ = statements;
}
// Return the break label for this for statement.
Unnamed_label*
break_label();
// Return the continue label for this for statement.
Unnamed_label*
continue_label();
// Set the break and continue labels for this statement.
void
set_break_continue_labels(Unnamed_label* break_label,
Unnamed_label* continue_label);
protected:
int
do_traverse(Traverse*);
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
bool
do_may_fall_through() const;
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
// The initialization statements. This may be NULL.
Block* init_;
// The condition. This may be NULL.
Expression* cond_;
// The statements to run after each iteration. This may be NULL.
Block* post_;
// The statements in the loop itself.
Block* statements_;
// The break label, if needed.
Unnamed_label* break_label_;
// The continue label, if needed.
Unnamed_label* continue_label_;
};
// A for statement over a range clause.
class For_range_statement : public Statement
{
public:
For_range_statement(Expression* index_var, Expression* value_var,
Expression* range, Location location)
: Statement(STATEMENT_FOR_RANGE, location),
index_var_(index_var), value_var_(value_var), range_(range),
statements_(NULL), break_label_(NULL), continue_label_(NULL)
{ }
// Add the statements.
void
add_statements(Block* statements)
{
go_assert(this->statements_ == NULL);
this->statements_ = statements;
}
// Return the break label for this for statement.
Unnamed_label*
break_label();
// Return the continue label for this for statement.
Unnamed_label*
continue_label();
protected:
int
do_traverse(Traverse*);
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
Expression*
make_range_ref(Named_object*, Temporary_statement*, Location);
Call_expression*
call_builtin(Gogo*, const char* funcname, Expression* arg, Location);
void
lower_range_array(Gogo*, Block*, Block*, Named_object*, Temporary_statement*,
Temporary_statement*, Temporary_statement*,
Block**, Expression**, Block**, Block**);
void
lower_range_slice(Gogo*, Block*, Block*, Named_object*, Temporary_statement*,
Temporary_statement*, Temporary_statement*,
Block**, Expression**, Block**, Block**);
void
lower_range_string(Gogo*, Block*, Block*, Named_object*, Temporary_statement*,
Temporary_statement*, Temporary_statement*,
Block**, Expression**, Block**, Block**);
void
lower_range_map(Gogo*, Map_type*, Block*, Block*, Named_object*,
Temporary_statement*, Temporary_statement*,
Temporary_statement*, Block**, Expression**, Block**,
Block**);
void
lower_range_channel(Gogo*, Block*, Block*, Named_object*,
Temporary_statement*, Temporary_statement*,
Temporary_statement*, Block**, Expression**, Block**,
Block**);
Statement*
lower_map_range_clear(Type*, Block*, Expression*, Named_object*,
Temporary_statement*, Location);
Statement*
lower_array_range_clear(Gogo*, Type*, Expression*, Block*,
Named_object*, Temporary_statement*,
Location);
// The variable which is set to the index value.
Expression* index_var_;
// The variable which is set to the element value. This may be
// NULL.
Expression* value_var_;
// The expression we are ranging over.
Expression* range_;
// The statements in the block.
Block* statements_;
// The break label, if needed.
Unnamed_label* break_label_;
// The continue label, if needed.
Unnamed_label* continue_label_;
};
// Class Case_clauses holds the clauses of a switch statement. This
// is built by the parser.
class Case_clauses
{
public:
Case_clauses()
: clauses_()
{ }
// Add a new clause. CASES is a list of case expressions; it may be
// NULL. IS_DEFAULT is true if this is the default case.
// STATEMENTS is a block of statements. IS_FALLTHROUGH is true if
// after the statements the case clause should fall through to the
// next clause.
void
add(Expression_list* cases, bool is_default, Block* statements,
bool is_fallthrough, Location location)
{
this->clauses_.push_back(Case_clause(cases, is_default, statements,
is_fallthrough, location));
}
// Return whether there are no clauses.
bool
empty() const
{ return this->clauses_.empty(); }
// Traverse the case clauses.
int
traverse(Traverse*);
// Lower for a nonconstant switch.
void
lower(Block*, Temporary_statement*, Unnamed_label*) const;
// Determine types of expressions. The Type parameter is the type
// of the switch value.
void
determine_types(Type*);
// Check types. The Type parameter is the type of the switch value.
bool
check_types(Type*);
// Return true if all the clauses are constant values.
bool
is_constant() const;
// Return true if these clauses may fall through to the statements
// following the switch statement.
bool
may_fall_through() const;
// Return the body of a SWITCH_EXPR when all the clauses are
// constants.
void
get_backend(Translate_context*, Unnamed_label* break_label,
std::vector<std::vector<Bexpression*> >* all_cases,
std::vector<Bstatement*>* all_statements) const;
// Dump the AST representation to a dump context.
void
dump_clauses(Ast_dump_context*) const;
private:
// For a constant switch we need to keep a record of constants we
// have already seen.
class Hash_integer_value;
class Eq_integer_value;
typedef Unordered_set_hash(Expression*, Hash_integer_value,
Eq_integer_value) Case_constants;
// One case clause.
class Case_clause
{
public:
Case_clause()
: cases_(NULL), statements_(NULL), is_default_(false),
is_fallthrough_(false), location_(Linemap::unknown_location())
{ }
Case_clause(Expression_list* cases, bool is_default, Block* statements,
bool is_fallthrough, Location location)
: cases_(cases), statements_(statements), is_default_(is_default),
is_fallthrough_(is_fallthrough), location_(location)
{ }
// Whether this clause falls through to the next clause.
bool
is_fallthrough() const
{ return this->is_fallthrough_; }
// Whether this is the default.
bool
is_default() const
{ return this->is_default_; }
// The location of this clause.
Location
location() const
{ return this->location_; }
// Traversal.
int
traverse(Traverse*);
// Lower for a nonconstant switch.
void
lower(Block*, Temporary_statement*, Unnamed_label*, Unnamed_label*) const;
// Determine types.
void
determine_types(Type*);
// Check types.
bool
check_types(Type*);
// Return true if all the case expressions are constant.
bool
is_constant() const;
// Return true if this clause may fall through to execute the
// statements following the switch statement. This is not the
// same as whether this clause falls through to the next clause.
bool
may_fall_through() const;
// Convert the case values and statements to the backend
// representation.
Bstatement*
get_backend(Translate_context*, Unnamed_label* break_label,
Case_constants*, std::vector<Bexpression*>* cases) const;
// Dump the AST representation to a dump context.
void
dump_clause(Ast_dump_context*) const;
private:
// The list of case expressions.
Expression_list* cases_;
// The statements to execute.
Block* statements_;
// Whether this is the default case.
bool is_default_;
// Whether this falls through after the statements.
bool is_fallthrough_;
// The location of this case clause.
Location location_;
};
friend class Case_clause;
// The type of the list of clauses.
typedef std::vector<Case_clause> Clauses;
// All the case clauses.
Clauses clauses_;
};
// A switch statement.
class Switch_statement : public Statement
{
public:
Switch_statement(Expression* val, Location location)
: Statement(STATEMENT_SWITCH, location),
val_(val), clauses_(NULL), break_label_(NULL)
{ }
// Add the clauses.
void
add_clauses(Case_clauses* clauses)
{
go_assert(this->clauses_ == NULL);
this->clauses_ = clauses;
}
// Return the break label for this switch statement.
Unnamed_label*
break_label();
protected:
int
do_traverse(Traverse*);
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
bool
do_may_fall_through() const;
private:
// The value to switch on. This may be NULL.
Expression* val_;
// The case clauses.
Case_clauses* clauses_;
// The break label, if needed.
Unnamed_label* break_label_;
};
// Class Type_case_clauses holds the clauses of a type switch
// statement. This is built by the parser.
class Type_case_clauses
{
public:
Type_case_clauses()
: clauses_()
{ }
// Add a new clause. TYPE is the type for this clause; it may be
// NULL. IS_FALLTHROUGH is true if this falls through to the next
// clause; in this case STATEMENTS will be NULL. IS_DEFAULT is true
// if this is the default case. STATEMENTS is a block of
// statements; it may be NULL.
void
add(Type* type, bool is_fallthrough, bool is_default, Block* statements,
Location location)
{
this->clauses_.push_back(Type_case_clause(type, is_fallthrough, is_default,
statements, location));
}
// Return whether there are no clauses.
bool
empty() const
{ return this->clauses_.empty(); }
// Traverse the type case clauses.
int
traverse(Traverse*);
// Check for duplicates.
void
check_duplicates() const;
// Lower to if and goto statements.
void
lower(Type*, Block*, Temporary_statement* descriptor_temp,
Unnamed_label* break_label) const;
// Return true if these clauses may fall through to the statements
// following the switch statement.
bool
may_fall_through() const;
// Dump the AST representation to a dump context.
void
dump_clauses(Ast_dump_context*) const;
private:
// One type case clause.
class Type_case_clause
{
public:
Type_case_clause()
: type_(NULL), statements_(NULL), is_default_(false),
location_(Linemap::unknown_location())
{ }
Type_case_clause(Type* type, bool is_fallthrough, bool is_default,
Block* statements, Location location)
: type_(type), statements_(statements), is_fallthrough_(is_fallthrough),
is_default_(is_default), location_(location)
{ }
// The type.
Type*
type() const
{ return this->type_; }
// Whether this is the default.
bool
is_default() const
{ return this->is_default_; }
// The location of this type clause.
Location
location() const
{ return this->location_; }
// Traversal.
int
traverse(Traverse*);
// Lower to if and goto statements.
void
lower(Type*, Block*, Temporary_statement* descriptor_temp,
Unnamed_label* break_label, Unnamed_label** stmts_label) const;
// Return true if this clause may fall through to execute the
// statements following the switch statement. This is not the
// same as whether this clause falls through to the next clause.
bool
may_fall_through() const;
// Dump the AST representation to a dump context.
void
dump_clause(Ast_dump_context*) const;
private:
// The type for this type clause.
Type* type_;
// The statements to execute.
Block* statements_;
// Whether this falls through--this is true for "case T1, T2".
bool is_fallthrough_;
// Whether this is the default case.
bool is_default_;
// The location of this type case clause.
Location location_;
};
friend class Type_case_clause;
// The type of the list of type clauses.
typedef std::vector<Type_case_clause> Type_clauses;
// All the type case clauses.
Type_clauses clauses_;
};
// A type switch statement.
class Type_switch_statement : public Statement
{
public:
Type_switch_statement(const std::string& name, Expression* expr,
Location location)
: Statement(STATEMENT_TYPE_SWITCH, location),
name_(name), expr_(expr), clauses_(NULL), break_label_(NULL)
{ }
// Add the clauses.
void
add_clauses(Type_case_clauses* clauses)
{
go_assert(this->clauses_ == NULL);
this->clauses_ = clauses;
}
// Return the break label for this type switch statement.
Unnamed_label*
break_label();
protected:
int
do_traverse(Traverse*);
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
bool
do_may_fall_through() const;
private:
// The name of the variable declared in the type switch guard. Empty if there
// is no variable declared.
std::string name_;
// The expression we are switching on if there is no variable.
Expression* expr_;
// The type case clauses.
Type_case_clauses* clauses_;
// The break label, if needed.
Unnamed_label* break_label_;
};
#endif // !defined(GO_STATEMENTS_H)