201506 CSE340 Lecture 12

CSE340 - Principles of
Programming Languages
Lecture 12:
Parser Implementation II
Javier Gonzalez-Sanchez
javiergs@asu.edu
BYENG M1-38
Office Hours: By appointment

Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 2
Review
Programming Assignment 2
Level 1
Review and Understand the Source Code
posted in Blackboard.
Particularly the use of DefaultMutableTreeNode)

Review
* Parser.java is the only file that you are allowed to modify

Review
Level 2
Modify the Source Code
to include the rules PROGRAM and BODY, EXPRESSION, X, Y, R
(from Grammar 2)

Review
<PROGRAM> à '{' <BODY> '}'
<BODY> à {<EXPRESSION>';'}
<EXPRESSION> à <X> {'|' <X>}
<X> à <Y> {'&' <Y>}
<Y> à ['!'] <R>
<R> à <E> {('>'|'<'|'=='|'!=') <E>}
<E> à <A> {(’+'|'-’) <A>}
<A> à {('*'|'/') }
 à ['-'] <C>
<C> à integer|
identifier|'(' <EXPRESSION> ')'

Level 3
The complete grammar for our language

KEYWORD {return, print}
STRING
Language
Actions
Expressions
(operators)
Instructions
Control
Structures
ARITHMETIC OPERATORS { +, -, *, /, =}
LOGIC OPERATORS { &, |, ! }
RELATIONAL OPERATORS {<, >, ==, !=}
KEYWORD { if, else, while, switch, case }
Data
INTEGER
FLOAT
HEXADECIMAL
CHAR
KEYWORD { void, int, char, string, float, boolean }
KEYWORD { true, false }
BINARY
Delimiter : ; , ( ) { } [ ]
Assignment 2 | Language
OCTAL
IDENTIFIER

Assignment 2 | 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 {('*'|'/') }
 à ['-'] <C>
<C> à integer | octal | hexadecimal | binary | true | false |
string | char | float | identifier|'(' <EXPRESSION> ')'

Assignment 2 | Input
Are there syntactical errors?
{
float a;
x = 0;
int x;
y = 1 + 1;
x = (0b11) +(05 – 0xFF34);
while (2 == "hi") {
a = 2 > (4 + Y);
if (true) { if( 2 + 2 ) {} else {} }
}
print ("hello" + "world");
}

{
int x;
x = 5;
x = 05;
x = 0x5ff;
x = 5.55;
x = "five";
x = ’5';
x = false;
}

{
int x;
float x;
string x;
char x;
void x;
boolean x;
}

{
x = "hello" + "world" – 'w' * 5 / 3.4;
x = y – hello & 0xffff | 05;
x = -7;
x = !y;
x = (cse340 + cse310) / cse101 ;
}

Assignment 2 | Code
------------ program(root);

Assignment 2 | Code
public static void RULE_PROGRAM() {
if (tokens.get(currentToken).getWord().equals(“{”)) {
currentToken++;
else
error(1);
RULE_BODY();
if (tokens.get(currentToken).getWord().equals(“}”))
currentToken++;
else
error(2);
}
PROGRAM

Assignment 2 | Code
public static void RULE_BODY() {
while (!tokens.get(currentToken).getWord().equals(“}”)) {
if (tokens.get(currentToken).getToken().equals(“identifier”)) {
RULE_ASSIGNMENT();
if (tokens.get(currentToken).getWord().equals(“;”)) {
currentToken++;
else error(3);
} else if (tokens.get(currentToken).getToken().equals(“int”) | ...) {
RULE_VARIABLE();
if (tokens.get(currentToken).getWord().equals(";")) {
currentToken++;
else error(3);
} else if (tokens.get(currentToken).getWord().equals(“while”)) {
RULE_WHILE();
} else if (tokens.get(currentToken).getWord().equals(“if”)) {
RULE_IF();
} else if (tokens.get(currentToken).getWord().equals(“return”)) {
RULE_RETURN();
if (tokens.get(currentToken).getWord().equals(“;”)) {
currentToken++;
else
error(3);
} else error(4);
}
}
BODY

Assignment 2 | Code
public static void RULE_ASSIGNMENT() {
}
ASSIGNMENT

Assignment 2 | Code
public static void RULE_VARIABLE() {
}
VARIABLE

Assignment 2 | Code
public static void RULE_WHILE() {
}
WHILE

Assignment 2 | Code
public static void RULE_IF() {
}
IF

Assignment 2 | Code
public static void RULE_RETURN() {
}
RETURN

Assignment 2 | Code
public static void RULE_PRINT () {
}
PRINT

Assignment 2 | Code
public static void RULE_C() {
}
C

PREDICTIVE
DESCENDENT
RECURSIVE
PARSER

Concepts
{
int a;
a = 0xFF + 0b111;
while (a != 05) {
if (true) {
a = 2.5e-1 / 7;
} else {
a = 'A’;
while(true) {
}
}
}
print ("hello");
}
PREDICTIVE
DESCENDENT
RECURSIVE
PARSER

Homework
Programming Assignment #2
(Complete Levels 1 to 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 12

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201506 CSE340 Lecture 12