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Parser with conditional functionality
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the comments that hug the left are basically all that are needed to be
implemented.  The function printToFile() should be used to print the
assembly code.
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@KevinDuarte
KevinDuarte committed Jul 9, 2015
1 parent 3feeeae commit 19b4511
Showing 1 changed file with 119 additions and 57 deletions.
176 changes: 119 additions & 57 deletions parser.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,12 +17,24 @@ symbol symbol_table[MAX_SYMBOL_TABLE_SIZE];

//the lexemelist fp
FILE * ifp;
//Most recent token
int TOKEN;
//most recent identifier or number
char IDENTIFIER[12];
int NUMBER;

//number of symbols in symbol_table
int numOfSymbols = 0;
//number of variables in symbol_table
int numOfVariables = 0;

//used for the branching in conditionals
int inConditional = 0;
int jumpLine = 0;

//counts the amount of lines of assembly that have been written
int lines = 0;

//number symbol values
typedef enum
{
Expand Down Expand Up @@ -102,15 +114,28 @@ int isRelationalOperator(int token)
{
return(token == eqlsym || token == neqsym || token == lessym || token == leqsym || token == gtrsym || token == geqsym);
}

//returns the symbol/indentifier with the given name
symbol getSymbol()
symbol getSymbol(char identifier[])
{
int i;
int i, found = 0;
for(i = 0; i < numOfVariables; i++)
{
if(strcmp(symbol_table[i].name, IDENTIFIER))
if(strcmp(symbol_table[i].name, identifier))
return symbol_table[i];
}
if(found == 0)
ERROR("Error number 11, undeclared identifier.");
}

//used to print the assembly code to the output file
void printToFile(char op[], int L, int M)
{
//if you are in a conditional, it does not print
if(inConditional != 0)
return;

//print to the file here
}


Expand All @@ -129,11 +154,15 @@ void FACTOR()
{
/*
if getSymbol() == variable
LOD getSymbol().L getSymbol().M
possible ERROR(variable has not been initialized)
LOD getSymbol().L getSymbol().M
printToFile()
lines++;
else if getSymbol() == constant
INC 0 1
LIT 0 getSymbol().val
printToFile()
lines += 2;
*/

GETTOKEN();
Expand All @@ -143,6 +172,8 @@ else if getSymbol() == constant
/*
INC 0 1
LIT 0 NUMBER
printToFile()
lines += 2;
*/

GETTOKEN();
Expand Down Expand Up @@ -174,6 +205,8 @@ void TERM()
/*
OPR 0 4 (for mult)
OPR 0 5 (for div)
printToFile()
lines +=2;
*/
}
}
Expand All @@ -186,6 +219,8 @@ void EXPRESSION()
if(minussym)
OPR 0 1
printToFile()
lines++;
*/
GETTOKEN();
}
Expand All @@ -197,6 +232,8 @@ OPR 0 1
/*
OPR 0 2 (for add)
OPR 0 3 (for sub)
printToFile()
lines +=2;
*/
}
}
Expand All @@ -209,6 +246,8 @@ void CONDITION()
EXPRESSION();
/*
OPR 0 6
printToFile()
lines ++;
*/
}
else
Expand All @@ -222,7 +261,9 @@ OPR 0 6
EXPRESSION();

/*
OPR 0 [conditionValue]
OPR 0 [conditionValue
printToFile()
lines ++;
*/
}
}
Expand All @@ -232,26 +273,14 @@ void STATEMENT()
//initialization
if(TOKEN == identsym)
{
//stores the name of the identifier that will be initialized
char name[12];
strcpy(name, IDENTIFIER);

//looks for the identifier in the symbol table
int i, found = 0;
for(i = 0; i < numOfSymbols; i++)
//if identifier is not a variable, produce error
if(getSymbol(IDENTIFIER).kind != 2)
{
if(strcmp(symbol_table[i].name, IDENTIFIER) == 0)
{
found = 1;
//if identifier is not a variable, produce error
if(symbol_table[i].kind != 2)
{
ERROR("Error number 12, assignment to constant or procedure not allowed.");
}
}
}
if(found == 0)
{
ERROR("Error number 11, undeclared identifier.");
ERROR("Error number 12, assignment to constant or procedure not allowed.");
}

GETTOKEN();
Expand All @@ -262,7 +291,9 @@ void STATEMENT()
GETTOKEN();
EXPRESSION();
/*
STO n.L n.M
STO getSymbol(name).L getSymbol(name).M
printToFile()
lines++;
*/
}
//procedure call (not in tiny PL/0)
Expand All @@ -274,23 +305,10 @@ STO n.L n.M
ERROR("Error number 14, call must be followed by an identifier.");
}

//looks for the identifier in the symbol table
int i, found = 0;
for(i = 0; i < numOfSymbols; i++)
{
if(strcmp(symbol_table[i].name, IDENTIFIER) == 0)
{
found = 1;
//if the identifier is not a procedure, produce an error
if(symbol_table[i].kind != 3)
{
ERROR("Error number 15, call of a constant or variable is meaningless.");
}
}
}
if(found == 0)
//if the identifier is not a procedure, produce an error
if(getSymbol(IDENTIFIER).kind != 3)
{
ERROR("Error number 11, undeclared identifier.");
ERROR("Error number 15, call of a constant or variable is meaningless.");
}

GETTOKEN();
Expand All @@ -315,32 +333,79 @@ STO n.L n.M
{
GETTOKEN();
CONDITION();
/*top of the stack has whether it is true or false
make branch here
*/

//top of the stack has whether it is true or false
if(TOKEN != thensym)
{
ERROR("Error number 16, then expected.");
}
GETTOKEN();
STATEMENT();

//after the condition, count how many instructions are written
int currentLines = lines;
inConditional++;
fpos_t filePos;
fgetpos(ifp, &filePos);

//loop ensures this is done twice
int i;
for(i = 0; i < 2; i++)
{
if(i == 1)
{
inConditional--;
//make branch here (lines contains the line that you jump to if the condition is not met)
//printToFile()

//returns the file to the previous position
fsetpos(ifp, &filePos);
lines = currentLines;
}
//the line for the branch is added
//lines++;

GETTOKEN();
STATEMENT();
}
}
else if(TOKEN == whilesym)
{
GETTOKEN();
CONDITION();
/*top of the stack has whether it is true or false
make branch here
*/
//top of the stack has whether it is true or false
if(TOKEN != dosym)
{
ERROR("Error number 18, do expected.");
}
GETTOKEN();
STATEMENT();
/*jump back to branch
*/

//after the condition, count how many instructions are written
int currentLines = lines;
inConditional++;
fpos_t filePos;
fgetpos(ifp, &filePos);

//loop ensures this is done twice
int i;
for(i = 0; i < 2; i++)
{
if(i == 1)
{
inConditional--;
//make branch here (lines contains the line that you jump to if the condition is not met)
//printToFile()

//returns the file to the previous position
fsetpos(ifp, &filePos);
lines = currentLines;
}
//the line for the branch is added
//lines++;

GETTOKEN();
STATEMENT();

//Jump back to condition (currentLines is where you jump to)
//printToFile()
//lines++
}
}
}

Expand Down Expand Up @@ -369,7 +434,6 @@ void BLOCK()
{
ERROR("Error number 3, = must be followed by a number.");
}
//the 0 is unnecissary
ENTER(1);
GETTOKEN();
} while(TOKEN == commasym);
Expand All @@ -389,7 +453,6 @@ void BLOCK()
{
ERROR("Error number 4, var must be followed by identifier.");
}
//what level do i input?
ENTER(2);
GETTOKEN();
} while(TOKEN == commasym);
Expand All @@ -400,15 +463,14 @@ void BLOCK()
}
GETTOKEN();
}
//procedure section, will not be used in module 3
//procedure section (will not be used in module 3)
while(TOKEN == procsym)
{
GETTOKEN();
if(TOKEN != identsym)
{
ERROR("Error number 4, procedure must be followed by identifier.");
}
//The 0 is useless here
ENTER(3);
GETTOKEN();
if(TOKEN != semicolonsym)
Expand All @@ -424,10 +486,10 @@ void BLOCK()
}
GETTOKEN();
}
//inc stack

/*
INC 0 (4 + numOfVariables)
printToFile()
lines++
*/

STATEMENT();
Expand Down

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