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jgs Compilers Lecture 15: Parser II Dr. Javier Gonzalez-Sanchez [email protected]

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jgs Previously …

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Dr. Javier Gonzalez-Sanchez | Compilers | 3 jgs Class Token

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Dr. Javier Gonzalez-Sanchez | Compilers | 4 jgs Class Automata

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Dr. Javier Gonzalez-Sanchez | Compilers | 5 jgs Class Lexer :: Your First Project

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Dr. Javier Gonzalez-Sanchez | Compilers | 6 jgs Class Main

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Dr. Javier Gonzalez-Sanchez | Compilers | 7 jgs Input

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jgs Parser

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Dr. Javier Gonzalez-Sanchez | Compilers | 9 jgs Class Main | Next Step

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Dr. Javier Gonzalez-Sanchez | Compilers | 10 jgs Class Parser

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Dr. Javier Gonzalez-Sanchez | Compilers | 11 jgs Input

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Dr. Javier Gonzalez-Sanchez | Compilers | 12 jgs Rules { 0; 1 + 2; 3 * (4 + hello); }

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Dr. Javier Gonzalez-Sanchez | Compilers | 13 jgs Homework https://github.com/javiergs/TheParser/

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Dr. Javier Gonzalez-Sanchez | Compilers | 14 jgs Homework You Need your Own Lexer

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jgs Next

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Dr. Javier Gonzalez-Sanchez | Compilers | 16 jgs Parser 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

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Dr. Javier Gonzalez-Sanchez | Compilers | 17 jgs Assignment 2 | Code PROGRAM Program this one

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Dr. Javier Gonzalez-Sanchez | Compilers | 18 jgs Assignment 2 | Code METHODS Program this one

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Dr. Javier Gonzalez-Sanchez | Compilers | 19 jgs Assignment 2 | Code BODY Program this one

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Dr. Javier Gonzalez-Sanchez | Compilers | 20 jgs Assignment 2 | Code PARAMS Program this one

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Dr. Javier Gonzalez-Sanchez | Compilers | 21 jgs Assignment 2 | Code PARAMS Program this one

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Dr. Javier Gonzalez-Sanchez | Compilers | 22 jgs Assignment 2 | Code public static void RULE_ASSIGNMENT() { } ASSIGNMENT Program this one

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Dr. Javier Gonzalez-Sanchez | Compilers | 23 jgs Parser public static void RULE_BODY() { while (!tokens.get(currentToken).getWord().equals(“}”)) { RULE_EXPRESSION(); if (tokens.get(currentToken).getWord().equals(“;”)) currentToken++; else error(3); } } BODY

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Dr. Javier Gonzalez-Sanchez | Compilers | 24 jgs Parser public static void RULE_EXPRESSION() { RULE_X(); while (tokens.get(currentToken).getWord().equals(“|”)) { currentToken++; RULE_X(); } } EXPRESSION

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Dr. Javier Gonzalez-Sanchez | Compilers | 25 jgs Parser public static void RULE_X() { RULE_Y(); while (tokens.get(currentToken).getWord().equals(“&”)) { currentToken++; RULE_Y(); } } X

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Dr. Javier Gonzalez-Sanchez | Compilers | 26 jgs Parser public static void RULE_Y() { if (tokens.get(currentToken).getWord().equals(“!”)) { currentToken++; } RULE_R(); } Y

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Dr. Javier Gonzalez-Sanchez | Compilers | 27 jgs Parser public static void RULE_R() { RULE_E(); while ( tokens.get(currentToken).getWord().equals(“<”) |tokens.get(currentToken).getWord().equals(“>”) |tokens.get(currentToken).getWord().equals(“==”) |tokens.get(currentToken).getWord().equals(“!=”) ) { currentToken++; RULE_E(); } } R

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Dr. Javier Gonzalez-Sanchez | Compilers | 28 jgs Parser public static void RULE_E() { RULE_A(); while (tokens.get(currentToken).getWord().equals(“-”) | tokens.get(currentToken).getWord().equals(“+”) ) { currentToken++; RULE_A(); } } E

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Dr. Javier Gonzalez-Sanchez | Compilers | 29 jgs Parser public static void RULE_A() { RULE_B(); while (tokens.get(currentToken).getWord().equals(“/”) | tokens.get(currentToken).getWord().equals(“*”) ) { currentToken++; RULE_B(); } } A

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Dr. Javier Gonzalez-Sanchez | Compilers | 30 jgs Parser public static void RULE_B() { if (tokens.get(currentToken).getWord().equals(“-”)) { currentToken++; } RULE_C(); } B

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Dr. Javier Gonzalez-Sanchez | Compilers | 31 jgs Parser public static void RULE_C() { if (tokens.get(currentToken).getToken().equals(“integer”)) { currentToken++; } else if (tokens.get(currentToken).getToken().equals(“identifier”)) { currentToken++; } else if (tokens.get(currentToken).getWord().equals(“(”)) { currentToken++; RULE_EXPRESSION(); if (tokens.get(currentToken).getWord().equals(“)”)) { currentToken++; } else error(4); } } else { error (5); } } C

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Dr. Javier Gonzalez-Sanchez | Compilers | 32 jgs Assignment 2 | Code public static void RULE_C() { } C

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Dr. Javier Gonzalez-Sanchez | Compilers | 33 jgs Assignment 2 | Code public static void RULE_VARIABLE() { } VARIABLE

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Dr. Javier Gonzalez-Sanchez | Compilers | 34 jgs Assignment 2 | Code public static void RULE_WHILE() { } WHILE

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Dr. Javier Gonzalez-Sanchez | Compilers | 35 jgs Assignment 2 | Code public static void RULE_IF() { } IF

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Dr. Javier Gonzalez-Sanchez | Compilers | 36 jgs Assignment 2 | Code public static void RULE_RETURN() { } RETURN

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Dr. Javier Gonzalez-Sanchez | Compilers | 37 jgs Assignment 2 | Code public static void RULE_CALL_METHOD () { } CALL_METHOD

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Dr. Javier Gonzalez-Sanchez | Compilers | 38 jgs Assignment 2 | Code public static void RULE_PARAM_VALUES () { } PARAM_VALUES

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Dr. Javier Gonzalez-Sanchez | Compilers | 39 jgs Questions

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jgs Compilers Javier Gonzalez-Sanchez, Ph.D. [email protected] Spring 2025 Copyright. These slides can only be used as study material for the Compilers course at Universidad Panamericana. They cannot be distributed or used for another purpose.