Dr. Philip Cannata 1 Programming Languages

Dr. Philip Cannata 2 10 Java (Object Oriented) ASP RDF (Horn Clause Deduction, Semantic Web) Relation Jython in Java This Course High Level Languages

Dr. Philip Cannata 3

Dr. Philip Cannata 4 { } a series of zero or more ( ) must pick one from a list [ ] pick none or one from a list expression -> term { ( + | - ) term } term -> factor { ( * | / ) factor } factor -> ( expression ) | number // the parenthesis are part of the grammar not the EBNF number -> { 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 } 6 * ( 11 – 7 ) /  High Level Overview of Grammar Concepts

Dr. Philip Cannata 5 Abstract Syntax Internal Parse Tree int main () { return 0 ; } Program (abstract syntax): Function = main; Return type = int params = Block: Return: Variable: return#main, LOCAL addr=0 IntValue: 0 Instance of a Programming Language: We ’ ll be starting with javacc  moving to ANTLR later

Dr. Philip Cannata 6 $ ls Makefile Parser.jj test Parser Files – javacc demo1 – similar to Chapter 1 in the Textbook but in java instead of scheme

Dr. Philip Cannata 7 PARSER_BEGIN(Parser) import java.io.*; import java.util.*; public class Parser { public static void main(String args[]) throws ParseException { Parser parser = new Parser (System.in); parser.ae(); } PARSER_END(Parser ) SKIP : { " " | "\t" | "\n" | "\r" | } TOKEN: { | } TOKEN: /* Literals */ { } TOKEN: { } void ae() : { Token n; } { n = { System.out.print("(num " + n +")"); } | list() } void list() : {} { LOOKAHEAD(2) { System.out.print(" (add ");} ( ae() )* { System.out.print(") "); } | { System.out.print(" (sub ");} ( ae() )* { System.out.print(") "); } } Parser Grammar Production Rules Tokens, Terminals Syntax and Grammar – Parser.jj

Dr. Philip Cannata 8 $ cat Makefile Parser.class: Parser.java javac *java Parser.java: Parser.jj javacc Parser.jj clean: rm *.class ParseException.java Parser.java ParserConstants.java ParserTokenManager.java SimpleCharStream.java Token.java TokenMgrError.java Parser Makefile - Makefile

Dr. Philip Cannata 9 $ make javacc Parser.jj Java Compiler Compiler Version 4.0 (Parser Generator) (type "javacc" with no arguments for help) Reading from file Parser.jj... File "TokenMgrError.java" does not exist. Will create one. File "ParseException.java" does not exist. Will create one. File "Token.java" does not exist. Will create one. File "SimpleCharStream.java" does not exist. Will create one. Parser generated successfully. javac *java Note: Parser.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. Making the Parser

Dr. Philip Cannata 10 $ cat test; cat test | java -cp "." Parser {+ 4 5 {- { } 6} 101 {+ 102}} (add (num 4)(num 5) (sub (add (num 1)(num 2)(num 3)) (num 6)) (num 101) (add (num 102)) ) Testing the Parser

Dr. Philip Cannata 11 $ ls AbstractSyntax.java Makefile Parser.jj calc.sh test $ cat calc.sh cat test cat test | java Parser cat test | java Parser | sed -e "s/add/+/g" -e "s/sub/-/g" -e "s/(num//g" -e "s/\([0-9]\))/\1/g" | tr -s " " " " | sed "s/^ *//" cat test | java Parser | sed -e "s/add/+/g" -e "s/sub/-/g" -e "s/(num//g" -e "s/\([0-9]\))/\1/g" | clisp --silent | grep -v ">" $./calc.sh {+ 4 5 {- { } 6} 101 {+ 102}} (add (num 4) (num 5) (sub (add (num 1) (num 2) (num 3)) (num 6)) (num 101) (add (num 102))) (+ 4 5 (- ( ) 6) 101 (+ 102)) 212 New Parser Files – javacc demo2 – similar to Chapter 2 in the Textbook but in java instead of scheme

Dr. Philip Cannata 12 1 op: “” intval: 0 children: top = sub = 1 nodeStack 1 Parse {+ 3 {+ 4 5 } 6} Abstract Syntax Tree Beginning

Dr. Philip Cannata 13 After recognizing {+ top = 1 sub = 2 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children: nodeStack 2 1 Abstract Syntax Tree

Dr. Philip Cannata 14 After recognizing {+ 3 top = 1 sub = 2 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children: 3 nodeStack 2 1 Abstract Syntax Tree 3 op: “int” intval: 3 children:

Dr. Philip Cannata 15 After recognizing {+ 3 {+ top = 1 sub = 4 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children: 3, 4 nodeStack Abstract Syntax Tree 3 op: “int” intval: 3 children: 4 op: “+” intval: 0 children:

Dr. Philip Cannata 16 After recognizing {+ 3 {+ 4 top = 1 sub = 4 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children: 3, 4 nodeStack Abstract Syntax Tree 3 op: “int” intval: 3 children: 4 op: “+” intval: 0 children: 5 5 op: “int” intval: 4 children:

Dr. Philip Cannata 17 After recognizing {+ 3 {+ 4 5 top = 1 sub = 4 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children: 3, 4 nodeStack Abstract Syntax Tree 3 op: “int” intval: 3 children: 4 op: “+” intval: 0 children: 5, 6 5 op: “int” intval: 4 children: 6 op: “int” intval: 5 children:

Dr. Philip Cannata 18 After recognizing {+ 3 {+ 4 5 } top = 1 sub = 2 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children:3, 4 nodeStack 2 1 Abstract Syntax Tree 3 op: “int” intval: 3 children: 4 op: “+” intval: 0 children: 5, 6 5 op: “int” intval: 4 children: 6 op: “int” intval: 5 children:

Dr. Philip Cannata 19 After recognizing {+ 3 {+ 4 5 } 6 top = 1 sub = 2 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children: 3, 4, 7 nodeStack 2 1 Abstract Syntax Tree 3 op: “int” intval: 3 children: 4 op: “+” intval: 0 children: 5, 6 5 op: “int” intval: 4 children: 6 op: “int” intval: 5 children: 7 op: “int” intval: 6 children:

Dr. Philip Cannata 20 After recognizing {+ 3 {+ 4 5 } 6 } top = 1 sub = 1 1 op: “” intval: 0 children: 2 2 op: “+” intval: 0 children: 3, 4, 7 nodeStack 1 Abstract Syntax Tree 3 op: “int” intval: 3 children: 4 op: “+” intval: 0 children: 5, 6 5 op: “int” intval: 4 children: 6 op: “int” intval: 5 children: 7 op: “int” intval: 6 children: Now print the Abstract Syntax Tree starting with top

Dr. Philip Cannata 21 $ ls AbstractSyntax.java Makefile Parser.jj calc.sh test $ cat calc.sh cat test cat test | java Parser $./calc.sh {+ 4 5 {- { } { } 6} 101 {+ 102}} Binary: top Binary: + 4 Binary: + 5 Binary: - Binary: + 1 Binary: + 2 Binary: + 3 Binary: Binary: Binary: Binary: - 6 Binary: Binary: Different Parser Files – javacc demo3 – Building a simple AST

Dr. Philip Cannata 22