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// go-linemap.h -- interface to location tracking -*- C++ -*-
// Copyright 2011 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_LINEMAP_H
#define GO_LINEMAP_H
#include "go-system.h"
// The backend must define a type named Location which holds
// information about a location in a source file. The only thing the
// frontend does with instances of Location is pass them back to the
// backend interface. The Location type must be assignable, and it
// must be comparable: i.e., it must support operator= and operator<.
// The type is normally passed by value rather than by reference, and
// it should support that efficiently. The type should be defined in
// "go-location.h".
#include "go-location.h"
// The Linemap class is a pure abstract interface, plus some static
// convenience functions. The backend must implement the interface.
class Linemap
{
public:
Linemap()
{
// Only one instance of Linemap is allowed to exist.
go_assert(Linemap::instance_ == NULL);
Linemap::instance_ = this;
}
virtual
~Linemap() { Linemap::instance_ = NULL; }
// Subsequent Location values will come from the file named
// FILE_NAME, starting at LINE_BEGIN. Normally LINE_BEGIN will be
// 0, but it will be non-zero if the Go source has a //line comment.
virtual void
start_file(const char* file_name, unsigned int line_begin) = 0;
// Subsequent Location values will come from the line LINE_NUMBER,
// in the current file. LINE_SIZE is the size of the line in bytes.
// This will normally be called for every line in a source file.
virtual void
start_line(unsigned int line_number, unsigned int line_size) = 0;
// Get a Location representing column position COLUMN on the current
// line in the current file.
virtual Location
get_location(unsigned int column) = 0;
// Stop generating Location values. This will be called after all
// input files have been read, in case any cleanup is required.
virtual void
stop() = 0;
protected:
// Return a special Location used for predeclared identifiers. This
// Location should be different from that for any actual source
// file. This location will be used for various different types,
// functions, and objects created by the frontend.
virtual Location
get_predeclared_location() = 0;
// Return a special Location which indicates that no actual location
// is known. This is used for undefined objects and for errors.
virtual Location
get_unknown_location() = 0;
// Return whether the argument is the Location returned by
// get_predeclared_location.
virtual bool
is_predeclared(Location) = 0;
// Return whether the argument is the Location returned by
// get_unknown_location.
virtual bool
is_unknown(Location) = 0;
// The single existing instance of Linemap.
static Linemap *instance_;
public:
// Following are convenience static functions, which allow us to
// access some virtual functions without explicitly passing around
// an instance of Linemap.
// Return the special Location used for predeclared identifiers.
static Location
predeclared_location()
{
go_assert(Linemap::instance_ != NULL);
return Linemap::instance_->get_predeclared_location();
}
// Return the special Location used when no location is known.
static Location
unknown_location()
{
go_assert(Linemap::instance_ != NULL);
return Linemap::instance_->get_unknown_location();
}
// Return whether the argument is the special location used for
// predeclared identifiers.
static bool
is_predeclared_location(Location loc)
{
go_assert(Linemap::instance_ != NULL);
return Linemap::instance_->is_predeclared(loc);
}
// Return whether the argument is the special location used when no
// location is known.
static bool
is_unknown_location(Location loc)
{
go_assert(Linemap::instance_ != NULL);
return Linemap::instance_->is_unknown(loc);
}
};
// The backend interface must define this function. It should return
// a fully implemented instance of Linemap.
extern Linemap* go_get_linemap();
#endif // !defined(GO_LINEMAP_H)
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