201506 CSE340 Lecture 18

CSE340 - Principles of
Programming Languages
Lecture 18:
Semantic Analysis II
Javier Gonzalez-Sanchez
BYENG M1-38
Office Hours: By appointment

Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 2
Semantic Analysis
1.  Declaration and Unicity. Review for uniqueness and that the variable
has been declared before its usage.
2.  Type Matching. Review that the types of variables match the values
assigned to them.
3.  Array’s indexes. Review that the indexes are integers.
4.  Conditions. Review that all expressions on the conditons return a
boolean value.
5.  Return type. Review that the value returned by a method match the
type of the method.
6.  Parameters. Review that the parameters in a method match in type
and number with the declaration of the method.

2. Type Matching

Type matching | Example 1
int x, y, z;
char p, q, r;
float a, b, c;
boolean foo;
void method() {
x = a * c + p;
}
x
*
+
a c p
=

Type matching | Cube
fill one sheet for
each operator in
the language
cube

OPERATOR int
ﬂoat
char
string
boolean
void
int
ﬂoat
char
string
boolean
void
cube

OPERATOR
+
int
float
char
string
boolean
void
int
int
float
X
string
X
X
float
float
float
X
string
X
X
char
X
X
X
string
X
X
string
string
string
string
string
string
X
boolean
X
X
X
string
X
X
void
X
X
X
X
X
X
cube

OPERATOR
&
int
ﬂoat
char
string
boolean
void
int
X
X
X
X
X
X
ﬂoat
X
X
X
X
X
X
char
X
X
X
X
X
X
string
X
X
X
X
X
X
boolean
X
X
X
X
boolean
X
void
X
X
X
X
X
X
cube

OPERATOR
<
int
ﬂoat
char
string
boolean
void
int
boolean
boolean
X
X
X
X
ﬂoat
boolean

boolean

X
X
X
X
char
X

X

X
X
X
X
string
X
X
X
X
X
X
boolean
X
X
X
X
X
X
void
X
X
X
X
X
X
cube

OPERATOR
=
int
ﬂoat
char
string
boolean
void
int
OK
X
X
X
X
X
ﬂoat
OK
OK
X
X
X
X
char
X
X
OK
X
X
X
string
X
X
X
OK
X
X
boolean
X
X
X
X
OK
X
void
X
X
X
X
X
OK
cube

OPERATOR
-
int
float
char
string
boolean
void
int
float
X
X
X
X
cube (- unary)
OPERATOR
+
int
float
char
string
boolean
void
int
int
float
X
string
X
X
float
float
float
X
string
X
X
char
X
X
X
string
X
X
string
string
string
string
string
string
X
boolean
X
X
X
string
X
X
void
X
X
X
X
X
X
cube (- binary)

int x, y, z;
char p, q, r;
float a, b, c;
boolean foo;
void method() {
x = a * c + p;
}
x
*
+
a c p
=

int a;
int c (int b) {
return b * 3 * 2 * 1 ;
}
void main () {
a = 1;
boolean a= c(14)/2 > 1;
}
cube for
matching types
symbol table
stack

Programming Assignment 3
Level 2
Reviewing Type Matching

Handwritten Notes
// Definition of the cube of types and operators
int cube [][][];
public static int OP_PLUS = 1;
public static int OP_MINUS = 2;
public static int OP_MULT = 3;
// …
public static int INTEGER = 1;
public static int FLOAT = 2;
// …
cube [OP_PLUS][INTEGER][INTEGER] = INTEGER;
cube [OP_PLUS][FLOAT][INTEGER] = FLOAT;
cube [OP_PLUS][INTEGER][FLOAT] = FLOAT;

Grammar
<PROGRAM> à '{' <BODY> '}’
<BODY> à {<PRINT>';'|<ASSIGNMENT>';'|<VARIABLE>';’|<WHILE>|<IF>|<RETURN>';'}
<ASSIGNMENT> à identifier '=' <EXPRESSION>
<VARIABLE> à ('int'|'float'|'boolean'|'char’|'string'|'void')identifier
<WHILE> à 'while' '(' <EXPRESSION> ')' <PROGRAM>
<IF> à 'if' '(' <EXPRESSION> ')' <PROGRAM> ['else' <PROGRAM>]
<RETURN> à 'return'
<PRINT> à ’print’ ‘(‘ <EXPRESSION> ‘)’
<EXPRESSION> à <X> {'|' <X>}
<X> à <Y> {'&' <Y>}
<Y> à ['!'] <R>
<R> à <E> {('>'|'<'|'=='|'!=') <E>}
<E> à <A> {(’+'|'-’) <A>}
<A> à <B> {('*'|'/') <B>}
<B> à ['-'] <C>
<C> à integer | octal | hexadecimal | binary | true | false |
string | char | float | identifier|'(' <EXPRESSION> ')'

Assignment 2 | Code
C
1.
// except for the open parenthesis
SemanticAnalizer.pushStack(
tokens.get(currentToken).getToken()
);

Parser
1. Store in a flag (operatorWasUSed):
Did the operator ‘-’ exist?
2.
if (operatorWasUsed)
String x = SemanticAnalizer.popStack();
String result = SemanticAnalizer.checkCube (x, “-” );
SemanticAnalizer.pushStack(result);
}

Parser
1. Store in a flag (twiceHere):
Did we pass this point twice?
3.
if (twiceHere)
String y = SemanticAnalizer.popStack();
String result = SemanticAnalizer.checkCube (x, y, operator );
twiceHere = false; // reset the flag
}
2. Store the operator that
creates the loop?

Parser
3.
if (twiceHere)
}
creates the loop?

Parser
1. Store in a flag (operatorWasUSed):
Did the operator ‘-’ exist?
2.
if (operatorWasUsed)
String result = SemanticAnalizer.checkCube (x, “!” );
}

Parser
2.
if (twiceHere)
String result = SemanticAnalizer.checkCube (x, y, “&” );
}

Assignment 2 | Code
String result = SemanticAnalizer.checkCube (x, y, “=” );
if (!result.equals(“OK”) {
error(2);
}

Homework
Programming Assignment 3

CSE340 - Principles of Programming Languages
Javier Gonzalez-Sanchez
javiergs@asu.edu
Summer 2015
Disclaimer. These slides can only be used as study material for the class CSE340 at ASU. They cannot be distributed or used for another purpose.

201506 CSE340 Lecture 18

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201506 CSE340 Lecture 18