/*
 * Definitions for the interpreter.  The major defintion is that of a
 * ValueStruct that represents the types of values that may be computed in a
 * program.
 */
#ifndef interp_h
#define interp_h

/*
 * A major distinction in value types is between l-values and r-values.
 * L-values are those that represent memory locations, to which r-values can be
 * assigned.  The name prefixes "L" and "R" refer to the LHS and RHS
 * respectively of an assignment statement.
 */
typedef enum {
    LVAL,
    RVAL
} ValType;

/*
 * A value structure tag indicates the type of value that is stored in the val
 * union field.
 */
#include "val.h"

/*
 * A ValueStruct is a union of types of computable values.  A "type" in this
 * context means one of general value types, i.e., integer, real, boolean,
 * string, list, tuple, or function.
 *
 * There are a couple of misnomers remnant from the Modula-2 code.
 * Specifically, a tuple value is called a "StructVal", and a function value is
 * called a "ProcVal".  There are also some remnant Modula-2 value types that
 * are not currently used.  These misnomers and left-over types are retained
 * for compilation purposes, pending some may-never-happen global refactoriing
 * of the code.
 */
typedef struct Val {
    ValType LorR;	/* Is it an l- or r-value. */
    ValTag tag;		/* Tag indicating the general type of value, ie., a
			   tag for the val union */
    TypeStruct type;	/* The full type struct, needed for structured vals. */
    int size;		/* The stored value of TypeSize(val) */
    union {

	/* The following 7 fields are for the diffent types of r-values. */
	int IntVal;	/* An integer value */
	double RealVal;	/* A real value */
	bool BoolVal;	/* A boolean value */
	struct StringStruct* StringVal;/* A string value */
	char *StructVal; /* A structured, aka tuple value */
	struct ListStruct* ListVal;	 /* A list value */
	struct Sym *ProcVal;	/* A proc, aka op function value
				   (unevaluated). */

	/* The next field is for an l-value.  It points to a value in a storage
         * pool. */
	char *LVal;	/* The value of an l-value is its storage pointer. */

	/* The following 5 fields are vestigial from Modula-2 */
	long LIntVal;	/* A long int value -- dumb since sizeof(int)
			     virtually always = sizeof(long) */
	double LRealVal;/* A long real value */
	char CharVal;	/* A char value, including char subranges */
	long SetVal;	/* A set value */
	char *PtrVal;	/* A pointer, aka ref value */
    } val;
} Value;

typedef Value *ValueStruct;

/*
 * Interpreter runtime exit statuses
 */
typedef enum {
    OKStatus,		/* Execution terminated normally. */
    NilPointerStatus,	/* Abnormal termination -- ref through nil pointer */
    NilProcStatus,	/* Abnormal termination -- ref through nil proc var */
    NilTypeStatus,	/* Abnormal termination -- ref through nil type */
    MemOutStatus,	/* Abnormal termination -- out of memory */
    ArrayBndStatus,	/* Abnormal termination -- array index out of bnds */
    StackOverStatus	/* Abnormal termination -- stack overflow */
} ExitStatus;


/*
 * Static pool and runtime stack structures.
 */
static int STATICSIZE = 25000;
static int ENVIRSIZE = 200;
static int STACKSIZE = 25000;
static int DISPLAYSIZE = 1000;    /* Raise this because new syntax to allow
                                     keywordless obj defs can lead to lots of
                                     excess nesting.  Some use of the error
				     token in parser.y might fix it, but
				     dont' feel like dealing with it that way
				     right now. */
#ifdef USEWITHCPP
extern "C"
#endif
char *StaticPool;	/* The static storage pool for global vars. */
#ifdef USEWITHCPP
extern "C"
#endif
char *EnvirPool;	/* The static storage pool for environment vars. */
#ifdef USEWITHCPP
extern "C"
#endif
char *Stack;		/* The runtime stack for parms and locals. */
#ifdef USEWITHCPP
extern "C"
#endif
char **Display;		/* The runtime display */
#ifdef USEWITHCPP
extern "C"
#endif
char *tos;		/* The current top of stack pointer. */
#ifdef USEWITHCPP
extern "C"
#endif
char *ftos;		/* Top of stack pointer used during parm binding. */


/*
 * Some handy macros for the basic types associated with values.  See isInt,
 * etc. in type-preds.h
 */
#define isIntV(v) (isInt(v->tag))
#define isLIntV(v) (isLongInt(v->tag))
#define isRealV(v) (isReal(v->tag))
#define isLRealV(v) (isLongReal(v->tag))
#define isCharV(v) (isChar(v->tag))
#define isBoolV(v) (isBool(v->tag))


/*
 * Visible functions
 */
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct interp();
#ifdef USEWITHCPP
extern "C"
#endif
void interpStmts(nodep);
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct interpExpr();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doExprSeq();
#ifdef USEWITHCPP
extern "C"
#endif
void doAssmnt();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doProcCall();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doCast();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doMult();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doDiv();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doMod();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doRealDiv();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doPlus();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doMinus();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doUnyPlus();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doUnyMinus();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doAnd();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doOr();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doXOr();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doImplies();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doIff();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doIfExpr();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doNot();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doEq();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doNotEq();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doLess();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doGreater();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doLessEq();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doGreaterEq();
#ifdef USEWITHCPP
extern "C"
#endif
bool SetContains();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doIn();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doLen();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doListConstructor();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doDotDot();
#ifdef USEWITHCPP
extern "C"
#endif
int SetNormalize();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doDesignator();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doQidRecord();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct lvalue();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct designator();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doArrayRef();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct doArraySliceRef();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct RecordRef();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct PointerRef();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct QidRef();
#ifdef USEWITHCPP
extern "C"
#endif
struct Sym *QuickLookupQid();
#ifdef USEWITHCPP
extern "C"
#endif
bool isGlobal();
#ifdef USEWITHCPP
extern "C"
#endif
char *GetAddr();
#ifdef USEWITHCPP
extern "C"
#endif
char *GetFormalAddr();
#ifdef USEWITHCPP
extern "C"
#endif
char *StaticAddr();
#ifdef USEWITHCPP
extern "C"
#endif
char *StackAddr();
#ifdef USEWITHCPP
extern "C"
#endif
void PushActRec();
#ifdef USEWITHCPP
extern "C"
#endif
char *GetTos();
#ifdef USEWITHCPP
extern "C"
#endif
char *GetFTos();
#ifdef USEWITHCPP
extern "C"
#endif
void SetTos();
#ifdef USEWITHCPP
extern "C"
#endif
void SetFTos();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct MakeVal();
#ifdef USEWITHCPP
extern "C"
#endif
ValTag ValueTag();
#ifdef USEWITHCPP
extern "C"
#endif
int Integerize();
#ifdef USEWITHCPP
extern "C"
#endif
int LIntegerize();
#ifdef USEWITHCPP
extern "C"
#endif
void InitInterp();
#ifdef USEWITHCPP
extern "C"
#endif
ValueStruct eval();
#ifdef USEWITHCPP
extern "C"
#endif
void push();
#ifdef USEWITHCPP
extern "C"
#endif
char* pop();
#ifdef USEWITHCPP
extern "C"
#endif
char* top();

#endif