tclcompcmds.c

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	    /*
	     * Jump to the end of the "if" command. Both jumpFalseFixupArray and
	     * jumpEndFixupArray are indexed by "jumpIndex".
	     */
	    
	    if (jumpEndFixupArray.next >= jumpEndFixupArray.end) {
		TclExpandJumpFixupArray(&jumpEndFixupArray);
	    }
	    jumpEndFixupArray.next++;
	    TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP,
	            &(jumpEndFixupArray.fixup[jumpIndex]));
	    
	    /*
	     * Fix the target of the jumpFalse after the test. Generate a 4 byte
	     * jump if the distance is > 120 bytes. This is conservative, and
	     * ensures that we won't have to replace this jump if we later also
	     * need to replace the proceeding jump to the end of the "if" with a
	     * 4 byte jump.
	     */

	    jumpDist = (envPtr->codeNext - envPtr->codeStart)
	            - jumpFalseFixupArray.fixup[jumpIndex].codeOffset;
	    if (TclFixupForwardJump(envPtr,
	            &(jumpFalseFixupArray.fixup[jumpIndex]), jumpDist, 120)) {
		/*
		 * Adjust the code offset for the proceeding jump to the end
		 * of the "if" command.
		 */
		
		jumpEndFixupArray.fixup[jumpIndex].codeOffset += 3;
	    }
	} else if (boolVal) {
	    /* 
	     *We were processing an "if 1 {...}"; stop compiling
	     * scripts
	     */

	    compileScripts = 0;
	} else {
	    /* 
	     *We were processing an "if 0 {...}"; reset so that
	     * the rest (elseif, else) is compiled correctly
	     */

	    realCond = 1;
	    compileScripts = 1;
	} 

	tokenPtr += (tokenPtr->numComponents + 1);
	wordIdx++;
    }

    /*
     * Restore the current stack depth in the environment; the 
     * "else" clause (or its default) will add 1 to this.
     */

    envPtr->currStackDepth = savedStackDepth;

    /*
     * Check for the optional else clause. Do not compile
     * anything if this was an "if 1 {...}" case.
     */

    if ((wordIdx < numWords)
	    && (tokenPtr->type == TCL_TOKEN_SIMPLE_WORD)) {
	/*
	 * There is an else clause. Skip over the optional "else" word.
	 */

	word = tokenPtr[1].start;
	numBytes = tokenPtr[1].size;
	if ((numBytes == 4) && (strncmp(word, "else", 4) == 0)) {
	    tokenPtr += (tokenPtr->numComponents + 1);
	    wordIdx++;
	    if (wordIdx >= numWords) {
		Tcl_ResetResult(interp);
		Tcl_AppendToObj(Tcl_GetObjResult(interp),
		        "wrong # args: no script following \"else\" argument", -1);
		code = TCL_ERROR;
		goto done;
	    }
	}

	if (compileScripts) {
	    /*
	     * Compile the else command body.
	     */
	    
	    code = TclCompileCmdWord(interp, tokenPtr+1,
		    tokenPtr->numComponents, envPtr);
	    if (code != TCL_OK) {
		if (code == TCL_ERROR) {
		    sprintf(buffer, "\n    (\"if\" else script line %d)",
			    interp->errorLine);
		    Tcl_AddObjErrorInfo(interp, buffer, -1);
		}
		goto done;
	    }
	}

	/*
	 * Make sure there are no words after the else clause.
	 */
	
	wordIdx++;
	if (wordIdx < numWords) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendToObj(Tcl_GetObjResult(interp),
		    "wrong # args: extra words after \"else\" clause in \"if\" command", -1);
	    code = TCL_ERROR;
	    goto done;
	}
    } else {
	/*
	 * No else clause: the "if" command's result is an empty string.
	 */

	if (compileScripts) {
	    TclEmitPush(TclRegisterNewLiteral(envPtr, "", 0), envPtr);
	}
    }

    /*
     * Fix the unconditional jumps to the end of the "if" command.
     */
    
    for (j = jumpEndFixupArray.next;  j > 0;  j--) {
	jumpIndex = (j - 1);	/* i.e. process the closest jump first */
	jumpDist = (envPtr->codeNext - envPtr->codeStart)
	        - jumpEndFixupArray.fixup[jumpIndex].codeOffset;
	if (TclFixupForwardJump(envPtr,
	        &(jumpEndFixupArray.fixup[jumpIndex]), jumpDist, 127)) {
	    /*
	     * Adjust the immediately preceeding "ifFalse" jump. We moved
	     * it's target (just after this jump) down three bytes.
	     */

	    unsigned char *ifFalsePc = envPtr->codeStart
	            + jumpFalseFixupArray.fixup[jumpIndex].codeOffset;
	    unsigned char opCode = *ifFalsePc;
	    if (opCode == INST_JUMP_FALSE1) {
		jumpFalseDist = TclGetInt1AtPtr(ifFalsePc + 1);
		jumpFalseDist += 3;
		TclStoreInt1AtPtr(jumpFalseDist, (ifFalsePc + 1));
	    } else if (opCode == INST_JUMP_FALSE4) {
		jumpFalseDist = TclGetInt4AtPtr(ifFalsePc + 1);
		jumpFalseDist += 3;
		TclStoreInt4AtPtr(jumpFalseDist, (ifFalsePc + 1));
	    } else {
		panic("TclCompileIfCmd: unexpected opcode updating ifFalse jump");
	    }
	}
    }

    /*
     * Free the jumpFixupArray array if malloc'ed storage was used.
     */

    done:
    envPtr->currStackDepth = savedStackDepth + 1;
    TclFreeJumpFixupArray(&jumpFalseFixupArray);
    TclFreeJumpFixupArray(&jumpEndFixupArray);
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileIncrCmd --
 *
 *	Procedure called to compile the "incr" command.
 *
 * Results:
 *	The return value is a standard Tcl result, which is TCL_OK if
 *	compilation was successful. If an error occurs then the
 *	interpreter's result contains a standard error message and TCL_ERROR
 *	is returned. If the command is too complex for TclCompileIncrCmd,
 *	TCL_OUT_LINE_COMPILE is returned indicating that the incr command
 *	should be compiled "out of line" by emitting code to invoke its
 *	command procedure at runtime.
 *
 * Side effects:
 *	Instructions are added to envPtr to execute the "incr" command
 *	at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileIncrCmd(interp, parsePtr, envPtr)
    Tcl_Interp *interp;		/* Used for error reporting. */
    Tcl_Parse *parsePtr;	/* Points to a parse structure for the
				 * command created by Tcl_ParseCommand. */
    CompileEnv *envPtr;		/* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr, *incrTokenPtr;
    int simpleVarName, isScalar, localIndex, haveImmValue, immValue;
    int code = TCL_OK;

    if ((parsePtr->numWords != 2) && (parsePtr->numWords != 3)) {
	Tcl_ResetResult(interp);
	Tcl_AppendToObj(Tcl_GetObjResult(interp),
	        "wrong # args: should be \"incr varName ?increment?\"", -1);
	return TCL_ERROR;
    }

    varTokenPtr = parsePtr->tokenPtr
	    + (parsePtr->tokenPtr->numComponents + 1);

    code = TclPushVarName(interp, varTokenPtr, envPtr, 
	    (TCL_NO_LARGE_INDEX | TCL_CREATE_VAR),
	    &localIndex, &simpleVarName, &isScalar);
    if (code != TCL_OK) {
	goto done;
    }

    /*
     * If an increment is given, push it, but see first if it's a small
     * integer.
     */

    haveImmValue = 0;
    immValue = 0;
    if (parsePtr->numWords == 3) {
	incrTokenPtr = varTokenPtr + (varTokenPtr->numComponents + 1);
	if (incrTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
	    CONST char *word = incrTokenPtr[1].start;
	    int numBytes = incrTokenPtr[1].size;
	    int validLength = TclParseInteger(word, numBytes);
	    long n;

	    /*
	     * Note there is a danger that modifying the string could have
	     * undesirable side effects.  In this case, TclLooksLikeInt and
	     * TclGetLong do not have any dependencies on shared strings so we
	     * should be safe.
	     */

	    if (validLength == numBytes) {
		int code;
		Tcl_Obj *longObj = Tcl_NewStringObj(word, numBytes);
		Tcl_IncrRefCount(longObj);
		code = Tcl_GetLongFromObj(NULL, longObj, &n);
		Tcl_DecrRefCount(longObj);
		if ((code == TCL_OK) && (-127 <= n) && (n <= 127)) {
		    haveImmValue = 1;
		    immValue = n;
		}
	    }
	    if (!haveImmValue) {
		TclEmitPush(
			TclRegisterNewLiteral(envPtr, word, numBytes), envPtr);
	    }
	} else {
	    code = TclCompileTokens(interp, incrTokenPtr+1, 
	            incrTokenPtr->numComponents, envPtr);
	    if (code != TCL_OK) {
		goto done;
	    }
	}
    } else {			/* no incr amount given so use 1 */
	haveImmValue = 1;
	immValue = 1;
    }
    
    /*
     * Emit the instruction to increment the variable.
     */

    if (simpleVarName) {
	if (isScalar) {
	    if (localIndex >= 0) {
		if (haveImmValue) {
		    TclEmitInstInt1(INST_INCR_SCALAR1_IMM, localIndex, envPtr);
		    TclEmitInt1(immValue, envPtr);
		} else {
		    TclEmitInstInt1(INST_INCR_SCALAR1, localIndex, envPtr);
		}
	    } else {
		if (haveImmValue) {
		    TclEmitInstInt1(INST_INCR_SCALAR_STK_IMM, immValue, envPtr);
		} else {
		    TclEmitOpcode(INST_INCR_SCALAR_STK, envPtr);
		}
	    }
	} else {
	    if (localIndex >= 0) {
		if (haveImmValue) {
		    TclEmitInstInt1(INST_INCR_ARRAY1_IMM, localIndex, envPtr);
		    TclEmitInt1(immValue, envPtr);
		} else {
		    TclEmitInstInt1(INST_INCR_ARRAY1, localIndex, envPtr);
		}
	    } else {
		if (haveImmValue) {
		    TclEmitInstInt1(INST_INCR_ARRAY_STK_IMM, immValue, envPtr);
		} else {
		    TclEmitOpcode(INST_INCR_ARRAY_STK, envPtr);
		}
	    }
	}
    } else {			/* non-simple variable name */
	if (haveImmValue) {
	    TclEmitInstInt1(INST_INCR_STK_IMM, immValue, envPtr);
	} else {
	    TclEmitOpcode(INST_INCR_STK, envPtr);
	}
    }
	
    done:
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileLappendCmd --
 *
 *	Procedure called to compile the "lappend" command.
 *
 * Results:
 *	The return value is a standard Tcl result, which is normally TCL_OK
 *	unless there was an error while parsing string. If an error occurs
 *	then the interpreter's result contains a standard error message. If
 *	complation fails because the command requires a second level of
 *	substitutions, TCL_OUT_LINE_COMPILE is returned indicating that the
 *	command should be compiled "out of line" by emitting code to
 *	invoke its command procedure (Tcl_LappendObjCmd) at runtime.
 *
 * Side effects:
 *	Instructions are added to envPtr to execute the "lappend" command
 *	at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileLappendCmd(interp, parsePtr, envPtr)
    Tcl_Interp *interp;		/* Used for error reporting. */
    Tcl_Parse *parsePtr;	/* Points to a parse structure for the
				 * command created by Tcl_ParseCommand. */
    CompileEnv *envPtr;		/* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr, *valueTokenPtr;
    int simpleVarName, isScalar, localIndex, numWords;
    int code = TCL_OK;

    /*
     * If we're not in a procedure, don't compile.
     */
    if (envPtr->procPtr == NULL) {
	return TCL_OUT_LINE_COMPILE;
    }

    numWords = parsePtr->numWords;
    if (numWords == 1) {
	Tcl_ResetResult(interp);
	Tcl_AppendToObj(Tcl_GetObjResult(interp),
		"wrong # args: should be \"lappend varName ?value value ...?\"", -1);
	return TCL_ERROR;
    }
    if (numWords != 3) {
	/*
	 * LAPPEND instructions currently only handle one value appends
	 */
        return TCL_OUT_LINE_COMPILE;
    }

    /*
     * Decide if we can use a frame slot for the var/array name or if we
     * need to emit code to compute and push the name at runtime. We use a
     * frame slot (entry in the array of local vars) if we are compiling a
     * procedure body and if the name is simple text that does not include
     * namespace qualifiers. 
     */

    varTokenPtr = parsePtr->tokenPtr
	    + (parsePtr->tokenPtr->numComponents + 1);

    code = TclPushVarName(interp, varTokenPtr, envPtr, TCL_CREATE_VAR,
	    &localIndex, &simpleVarName, &isScalar);
    if (code != TCL_OK) {
	goto done;
    }

    /*
     * If we are doing an assignment, push the new value.
     * In the no values case, create an empty object.
     */

    if (numWords > 2) {
	valueTokenPtr = varTokenPtr + (varTokenPtr->numComponents + 1);
	if (valueTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
	    TclEmitPush(TclRegisterNewLiteral(envPtr, 
		    valueTokenPtr[1].start, valueTokenPtr[1].size), envPtr);
	} else {
	    code = TclCompileTokens(interp, valueTokenPtr+1,
	            valueTokenPtr->numComponents, envPtr);
	    if (code != TCL_OK) {
		goto done;
	    }
	}
    }

    /*
     * Emit instructions to set/get the variable.
     */

    /*
     * The *_STK opcodes should be refactored to make better use of existing
     * LOAD/STORE instructions.
     */
    if (simpleVarName) {
	if (isScalar) {
	    if (localIndex >= 0) {
		if (localIndex <= 255) {
		    TclEmitInstInt1(INST_LAPPEND_SCALAR1, localIndex, envPtr);
		} else {
		    TclEmitInstInt4(INST_LAPPEND_SCALAR4, localIndex, envPtr);
		}
	    } else {
		TclEmitOpcode(INST_LAPPEND_STK, envPtr);
	    }
	} else {
	    if (localIndex >= 0) {
		if (localIndex <= 255) {
		    TclEmitInstInt1(INST_LAPPEND_ARRAY1, localIndex, envPtr);
		} else {
		    TclEmitInstInt4(INST_LAPPEND_ARRAY4, localIndex, envPtr);
		}
	    } else {
		TclEmitOpcode(INST_LAPPEND_ARRAY_STK, envPtr);
	    }