tclcompexpr.c

来自「tcl是工具命令语言」· C语言 代码 · 共 964 行 · 第 1/2 页

			goto done;
		    }
		    tokenPtr += (tokenPtr->numComponents + 1);
		    
		    /*
		     * Check whether the "+" or "-" is unary.
		     */
		    
		    afterSubexprPtr = exprTokenPtr
			    + exprTokenPtr->numComponents+1;
		    if (tokenPtr == afterSubexprPtr) {
			TclEmitOpcode(((opIndex==OP_PLUS)?
			        INST_UPLUS : INST_UMINUS),
			        envPtr);
			break;
		    }
		    
		    /*
		     * The "+" or "-" is binary.
		     */
		    
		    code = CompileSubExpr(tokenPtr, infoPtr, envPtr);
		    if (code != TCL_OK) {
			goto done;
		    }
		    tokenPtr += (tokenPtr->numComponents + 1);
		    TclEmitOpcode(((opIndex==OP_PLUS)? INST_ADD : INST_SUB),
			    envPtr);
		    break;

	        case OP_LAND:
	        case OP_LOR:
		    code = CompileLandOrLorExpr(exprTokenPtr, opIndex,
			    infoPtr, envPtr, &endPtr);
		    if (code != TCL_OK) {
			goto done;
		    }
		    tokenPtr = endPtr;
		    break;
			
	        case OP_QUESTY:
		    code = CompileCondExpr(exprTokenPtr, infoPtr,
			    envPtr, &endPtr);
		    if (code != TCL_OK) {
			goto done;
		    }
		    tokenPtr = endPtr;
		    break;
		    
		default:
		    panic("CompileSubExpr: unexpected operator %d requiring special treatment\n",
		        opIndex);
	    } /* end switch on operator requiring special treatment */
	    infoPtr->hasOperators = 1;
	    break;

        default:
	    panic("CompileSubExpr: unexpected token type %d\n",
	            tokenPtr->type);
    }

    /*
     * Verify that the subexpression token had the required number of
     * subtokens: that we've advanced tokenPtr just beyond the
     * subexpression's last token. For example, a "*" subexpression must
     * contain the tokens for exactly two operands.
     */
    
    if (tokenPtr != (exprTokenPtr + exprTokenPtr->numComponents+1)) {
	LogSyntaxError(infoPtr);
	code = TCL_ERROR;
    }
    
    done:
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * CompileLandOrLorExpr --
 *
 *	This procedure compiles a Tcl logical and ("&&") or logical or
 *	("||") subexpression.
 *
 * Results:
 *	The return value is TCL_OK on a successful compilation and TCL_ERROR
 *	on failure. If TCL_OK is returned, a pointer to the token just after
 *	the last one in the subexpression is stored at the address in
 *	endPtrPtr. If TCL_ERROR is returned, then the interpreter's result
 *	contains an error message.
 *
 * Side effects:
 *	Adds instructions to envPtr to evaluate the expression at runtime.
 *
 *----------------------------------------------------------------------
 */

static int
CompileLandOrLorExpr(exprTokenPtr, opIndex, infoPtr, envPtr, endPtrPtr)
    Tcl_Token *exprTokenPtr;	 /* Points to TCL_TOKEN_SUB_EXPR token
				  * containing the "&&" or "||" operator. */
    int opIndex;		 /* A code describing the expression
				  * operator: either OP_LAND or OP_LOR. */
    ExprInfo *infoPtr;		 /* Describes the compilation state for the
				  * expression being compiled. */
    CompileEnv *envPtr;		 /* Holds resulting instructions. */
    Tcl_Token **endPtrPtr;	 /* If successful, a pointer to the token
				  * just after the last token in the
				  * subexpression is stored here. */
{
    JumpFixup shortCircuitFixup; /* Used to fix up the short circuit jump
				  * after the first subexpression. */
    JumpFixup lhsTrueFixup, lhsEndFixup;
    				 /* Used to fix up jumps used to convert the
				  * first operand to 0 or 1. */
    Tcl_Token *tokenPtr;
    int dist, code;
    int savedStackDepth = envPtr->currStackDepth;

    /*
     * Emit code for the first operand.
     */

    tokenPtr = exprTokenPtr+2;
    code = CompileSubExpr(tokenPtr, infoPtr, envPtr);
    if (code != TCL_OK) {
	goto done;
    }
    tokenPtr += (tokenPtr->numComponents + 1);

    /*
     * Convert the first operand to the result that Tcl requires:
     * "0" or "1". Eventually we'll use a new instruction for this.
     */
    
    TclEmitForwardJump(envPtr, TCL_TRUE_JUMP, &lhsTrueFixup);
    TclEmitPush(TclRegisterNewLiteral(envPtr, "0", 1), envPtr);
    TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP, &lhsEndFixup);
    dist = (envPtr->codeNext - envPtr->codeStart) - lhsTrueFixup.codeOffset;
    if (TclFixupForwardJump(envPtr, &lhsTrueFixup, dist, 127)) {
        badDist:
	panic("CompileLandOrLorExpr: bad jump distance %d\n", dist);
    }
    envPtr->currStackDepth = savedStackDepth;
    TclEmitPush(TclRegisterNewLiteral(envPtr, "1", 1), envPtr);
    dist = (envPtr->codeNext - envPtr->codeStart) - lhsEndFixup.codeOffset;
    if (TclFixupForwardJump(envPtr, &lhsEndFixup, dist, 127)) {
	goto badDist;
    }

    /*
     * Emit the "short circuit" jump around the rest of the expression.
     * Duplicate the "0" or "1" on top of the stack first to keep the
     * jump from consuming it.
     */

    TclEmitOpcode(INST_DUP, envPtr);
    TclEmitForwardJump(envPtr,
	    ((opIndex==OP_LAND)? TCL_FALSE_JUMP : TCL_TRUE_JUMP),
	    &shortCircuitFixup);

    /*
     * Emit code for the second operand.
     */

    code = CompileSubExpr(tokenPtr, infoPtr, envPtr);
    if (code != TCL_OK) {
	goto done;
    }
    tokenPtr += (tokenPtr->numComponents + 1);

    /*
     * Emit a "logical and" or "logical or" instruction. This does not try
     * to "short- circuit" the evaluation of both operands, but instead
     * ensures that we either have a "1" or a "0" result.
     */

    TclEmitOpcode(((opIndex==OP_LAND)? INST_LAND : INST_LOR), envPtr);

    /*
     * Now that we know the target of the forward jump, update it with the
     * correct distance.
     */

    dist = (envPtr->codeNext - envPtr->codeStart)
	    - shortCircuitFixup.codeOffset;
    TclFixupForwardJump(envPtr, &shortCircuitFixup, dist, 127);
    *endPtrPtr = tokenPtr;

    done:
    envPtr->currStackDepth = savedStackDepth + 1;
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * CompileCondExpr --
 *
 *	This procedure compiles a Tcl conditional expression:
 *	condExpr ::= lorExpr ['?' condExpr ':' condExpr]
 *
 * Results:
 *	The return value is TCL_OK on a successful compilation and TCL_ERROR
 *	on failure. If TCL_OK is returned, a pointer to the token just after
 *	the last one in the subexpression is stored at the address in
 *	endPtrPtr. If TCL_ERROR is returned, then the interpreter's result
 *	contains an error message.
 *
 * Side effects:
 *	Adds instructions to envPtr to evaluate the expression at runtime.
 *
 *----------------------------------------------------------------------
 */

static int
CompileCondExpr(exprTokenPtr, infoPtr, envPtr, endPtrPtr)
    Tcl_Token *exprTokenPtr;	/* Points to TCL_TOKEN_SUB_EXPR token
				 * containing the "?" operator. */
    ExprInfo *infoPtr;		/* Describes the compilation state for the
				 * expression being compiled. */
    CompileEnv *envPtr;		/* Holds resulting instructions. */
    Tcl_Token **endPtrPtr;	/* If successful, a pointer to the token
				 * just after the last token in the
				 * subexpression is stored here. */
{
    JumpFixup jumpAroundThenFixup, jumpAroundElseFixup;
				/* Used to update or replace one-byte jumps
				 * around the then and else expressions when
				 * their target PCs are determined. */
    Tcl_Token *tokenPtr;
    int elseCodeOffset, dist, code;
    int savedStackDepth = envPtr->currStackDepth;

    /*
     * Emit code for the test.
     */

    tokenPtr = exprTokenPtr+2;
    code = CompileSubExpr(tokenPtr, infoPtr, envPtr);
    if (code != TCL_OK) {
	goto done;
    }
    tokenPtr += (tokenPtr->numComponents + 1);
    
    /*
     * Emit the jump to the "else" expression if the test was false.
     */
    
    TclEmitForwardJump(envPtr, TCL_FALSE_JUMP, &jumpAroundThenFixup);

    /*
     * Compile the "then" expression. Note that if a subexpression is only
     * a primary, we need to try to convert it to numeric. We do this to
     * support Tcl's policy of interpreting operands if at all possible as
     * first integers, else floating-point numbers.
     */

    infoPtr->hasOperators = 0;
    code = CompileSubExpr(tokenPtr, infoPtr, envPtr);
    if (code != TCL_OK) {
	goto done;
    }
    tokenPtr += (tokenPtr->numComponents + 1);
    if (!infoPtr->hasOperators) {
	TclEmitOpcode(INST_TRY_CVT_TO_NUMERIC, envPtr);
    }

    /*
     * Emit an unconditional jump around the "else" condExpr.
     */
    
    TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP,
	    &jumpAroundElseFixup);

    /*
     * Compile the "else" expression.
     */

    envPtr->currStackDepth = savedStackDepth;
    elseCodeOffset = (envPtr->codeNext - envPtr->codeStart);
    infoPtr->hasOperators = 0;
    code = CompileSubExpr(tokenPtr, infoPtr, envPtr);
    if (code != TCL_OK) {
	goto done;
    }
    tokenPtr += (tokenPtr->numComponents + 1);
    if (!infoPtr->hasOperators) {
	TclEmitOpcode(INST_TRY_CVT_TO_NUMERIC, envPtr);
    }

    /*
     * Fix up the second jump around the "else" expression.
     */

    dist = (envPtr->codeNext - envPtr->codeStart)
	    - jumpAroundElseFixup.codeOffset;
    if (TclFixupForwardJump(envPtr, &jumpAroundElseFixup, dist, 127)) {
	/*
	 * Update the else expression's starting code offset since it
	 * moved down 3 bytes too.
	 */
	
	elseCodeOffset += 3;
    }
	
    /*
     * Fix up the first jump to the "else" expression if the test was false.
     */
    
    dist = (elseCodeOffset - jumpAroundThenFixup.codeOffset);
    TclFixupForwardJump(envPtr, &jumpAroundThenFixup, dist, 127);
    *endPtrPtr = tokenPtr;

    done:
    envPtr->currStackDepth = savedStackDepth + 1;
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * CompileMathFuncCall --
 *
 *	This procedure compiles a call on a math function in an expression:
 *	mathFuncCall ::= funcName '(' [condExpr {',' condExpr}] ')'
 *
 * Results:
 *	The return value is TCL_OK on a successful compilation and TCL_ERROR
 *	on failure. If TCL_OK is returned, a pointer to the token just after
 *	the last one in the subexpression is stored at the address in
 *	endPtrPtr. If TCL_ERROR is returned, then the interpreter's result
 *	contains an error message.
 *
 * Side effects:
 *	Adds instructions to envPtr to evaluate the math function at
 *	runtime.
 *
 *----------------------------------------------------------------------
 */

static int
CompileMathFuncCall(exprTokenPtr, funcName, infoPtr, envPtr, endPtrPtr)
    Tcl_Token *exprTokenPtr;	/* Points to TCL_TOKEN_SUB_EXPR token
				 * containing the math function call. */
    CONST char *funcName;	/* Name of the math function. */
    ExprInfo *infoPtr;		/* Describes the compilation state for the
				 * expression being compiled. */
    CompileEnv *envPtr;		/* Holds resulting instructions. */
    Tcl_Token **endPtrPtr;	/* If successful, a pointer to the token
				 * just after the last token in the
				 * subexpression is stored here. */
{
    Tcl_Interp *interp = infoPtr->interp;
    Interp *iPtr = (Interp *) interp;
    MathFunc *mathFuncPtr;
    Tcl_HashEntry *hPtr;
    Tcl_Token *tokenPtr, *afterSubexprPtr;
    int code, i;

    /*
     * Look up the MathFunc record for the function.
     */

    code = TCL_OK;
    hPtr = Tcl_FindHashEntry(&iPtr->mathFuncTable, funcName);
    if (hPtr == NULL) {
	Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		"unknown math function \"", funcName, "\"", (char *) NULL);
	code = TCL_ERROR;
	goto done;
    }
    mathFuncPtr = (MathFunc *) Tcl_GetHashValue(hPtr);

    /*
     * If not a builtin function, push an object with the function's name.
     */

    if (mathFuncPtr->builtinFuncIndex < 0) {
	TclEmitPush(TclRegisterNewLiteral(envPtr, funcName, -1), envPtr);
    }

    /*
     * Compile any arguments for the function.
     */

    tokenPtr = exprTokenPtr+2;
    afterSubexprPtr = exprTokenPtr + (exprTokenPtr->numComponents + 1);
    if (mathFuncPtr->numArgs > 0) {
	for (i = 0;  i < mathFuncPtr->numArgs;  i++) {
	    if (tokenPtr == afterSubexprPtr) {
		Tcl_ResetResult(interp);
		Tcl_AppendToObj(Tcl_GetObjResult(interp),
		        "too few arguments for math function", -1);
		code = TCL_ERROR;
		goto done;
	    }
	    code = CompileSubExpr(tokenPtr, infoPtr, envPtr);
	    if (code != TCL_OK) {
		goto done;
	    }
	    tokenPtr += (tokenPtr->numComponents + 1);
	}
	if (tokenPtr != afterSubexprPtr) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendToObj(Tcl_GetObjResult(interp),
		    "too many arguments for math function", -1);
	    code = TCL_ERROR;
	    goto done;
	} 
    } else if (tokenPtr != afterSubexprPtr) {
	Tcl_ResetResult(interp);
	Tcl_AppendToObj(Tcl_GetObjResult(interp),
		"too many arguments for math function", -1);
	code = TCL_ERROR;
	goto done;
    }
    
    /*
     * Compile the call on the math function. Note that the "objc" argument
     * count for non-builtin functions is incremented by 1 to include the
     * function name itself.
     */

    if (mathFuncPtr->builtinFuncIndex >= 0) { /* a builtin function */
	/*
	 * Adjust the current stack depth by the number of arguments
	 * of the builtin function. This cannot be handled by the 
	 * TclEmitInstInt1 macro as the number of arguments is not
	 * passed as an operand.
	 */

	if (envPtr->maxStackDepth < envPtr->currStackDepth) {
	    envPtr->maxStackDepth = envPtr->currStackDepth;
	}
	TclEmitInstInt1(INST_CALL_BUILTIN_FUNC1,
	        mathFuncPtr->builtinFuncIndex, envPtr);
	envPtr->currStackDepth -= mathFuncPtr->numArgs;
    } else {
	TclEmitInstInt1(INST_CALL_FUNC1, (mathFuncPtr->numArgs+1), envPtr);
    }
    *endPtrPtr = afterSubexprPtr;

    done:
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * LogSyntaxError --
 *
 *	This procedure is invoked after an error occurs when compiling an
 *	expression. It sets the interpreter result to an error message
 *	describing the error.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Sets the interpreter result to an error message describing the
 *	expression that was being compiled when the error occurred.
 *
 *----------------------------------------------------------------------
 */

static void
LogSyntaxError(infoPtr)
    ExprInfo *infoPtr;		/* Describes the compilation state for the
				 * expression being compiled. */
{
    int numBytes = (infoPtr->lastChar - infoPtr->expr);
    char buffer[100];

    sprintf(buffer, "syntax error in expression \"%.*s\"",
	    ((numBytes > 60)? 60 : numBytes), infoPtr->expr);
    Tcl_ResetResult(infoPtr->interp);
    Tcl_AppendStringsToObj(Tcl_GetObjResult(infoPtr->interp),
	    buffer, (char *) NULL);
}