jgs Compilers Lecture 20: Semantic Analysis III Dr. Javier Gonzalez-Sanchez jgonzalezs@up.edu.mx

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Dr. Javier Gonzalez-Sanchez | Compilers | 3 jgs Semantic Analysis 1. Declaration and Unicity. Review for uniqueness and that the variable has been declared before its usage. 2. Types. 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.

Dr. Javier Gonzalez-Sanchez | Compilers | 4 jgs Errors to be reported § Line : Variable not found § Line : Variable is already defined § Line : Incompatible types: type mismatch § Line : Incompatible types: expected boolean

Dr. Javier Gonzalez-Sanchez | Compilers | 5 jgs Errata

Dr. Javier Gonzalez-Sanchez | Compilers | 6 jgs Addition

Dr. Javier Gonzalez-Sanchez | Compilers | 7 jgs Logic Operators

Dr. Javier Gonzalez-Sanchez | Compilers | 8 jgs Test Case 1 1.{ 2.boolean boo; boolean foo; 3.int boo; int j; 4.int i; int minusfour; int k; 5.boolean k; 6.i = 4; 7.j = 3; 8.minusfour = boo; 9.while(i > 0) { 10. j = hello + 100 / 50; 11. while( j > 0) { 12. k = i*j; 13. print (k); 14. j = j-1; 15. } 16. i = i-1; 17.} 18.if (boo + minusfour) { 19. print (i); 20.} 21. 22.if (i < minusfour) { 23. print (j); 24.} 25.while (!i > minusfour) { 26. print (i); 27. i = i - 1; 28.} 29. 30.i = i + foo; 31.j = j + 1; 32.print (i); 33.print (j); 34.j = 100 > 90; 35.}

Dr. Javier Gonzalez-Sanchez | Compilers | 9 jgs Test Case 1 1.Line 2: variable is already defined 2.Line 4: variable is already defined 3.Line 8: incompatible types: type mismatch 4.Line 10: variable not found 5.Line 10: incompatible types: type mismatch 6.Line 18: boolean expression expected 7.Line 30: incompatible types: type mismatch 8.Line 34: incompatible types: type mismatch

Dr. Javier Gonzalez-Sanchez | Compilers | 10 jgs 3. Conditions

Dr. Javier Gonzalez-Sanchez | Compilers | 11 jgs Example { int a; int b; boolean c; a = 4; b = a + 1; if (a > b) { print (a); } } cube for matching types symbol table stack

Dr. Javier Gonzalez-Sanchez | Compilers | 12 jgs Grammar à '{' '}’ à {';'|';'|';’|||';'} à identifier '=' à ('int'|'float'|'boolean'|'char’|'string'|'void')identifier à 'while' '(' ')' à 'if' '(' ')' ['else' ] à 'return' à ’print’ ‘(‘ ‘)’ à {'|' } à {'&' } à ['!'] à {('>'|'<'|'=='|'!=') } à {(’+'|'-’) } à {('*'|'/') } à ['-'] à integer | octal | hexadecimal | binary | true | false | string | char | float | identifier|'(' ')'

Dr. Javier Gonzalez-Sanchez | Compilers | 13 jgs Conditions WHILE String x = SemanticAnalizer.popStack(); if (!x.equals(“boolean”) { error(3); }

Dr. Javier Gonzalez-Sanchez | Compilers | 14 jgs Conditions IF String x = SemanticAnalizer.popStack(); if (!x.equals(“boolean”) { error(3); }

Dr. Javier Gonzalez-Sanchez | Compilers | 15 jgs Semantic Analysis þDeclaration and Unicity. Review for uniqueness and that the variable has been declared before its usage. þType Matching. Review that the types of variables match the values assigned to them. ¨Array’s indexes. Review that the indexes are integers. þConditions. Review that all expressions on the conditions return a boolean value. ¨Return type. Review that the value returned by a method matches the type of the method. ¨Parameters. Review that the parameters in a method match in type and number with the declaration of the method.

Dr. Javier Gonzalez-Sanchez | Compilers | 16 jgs Assignment #3 public class SemanticAnalyzer { private static final Hashtable> symbolTable; private static final Stack stack; // create here a data structure for the cube of types public static Hashtable> getSymbolTable() public static void checkVariable(String type, String id) public static String isBoolean() public static String isTypeMatching() public static void stackPush (String type) public static String stackPop() private String calculateType(String type, String operator) private String calculateType(String type1, String type2, String operator) private static void error(Gui gui, int error, int line, String info) }

Dr. Javier Gonzalez-Sanchez | Compilers | 17 jgs Programming Assignment 3 Level 3 Reviewing Conditions

Dr. Javier Gonzalez-Sanchez | Compilers | 18 jgs A3 :: Review

Dr. Javier Gonzalez-Sanchez | Compilers | 19 jgs Homework Programming Assignment Full Semantic Analyzer

Dr. Javier Gonzalez-Sanchez | Compilers | 20 jgs Let Us Work 1. Functions: Grammar and Semantic Validation 2. Arrays: Grammar and Semantic Validation 3. Switch, For, and Do/While: Grammar and Semantic Validation 4. CallToMethod: Grammar and Semantic Validation

Dr. Javier Gonzalez-Sanchez | Compilers | 21 jgs Tool https:/ /tabatkins.github.io/ railroad-diagrams/generator.html

Dr. Javier Gonzalez-Sanchez | Compilers | 22 jgs Questions

jgs Compilers Javier Gonzalez-Sanchez, Ph.D. jgonzalezs@up.edu.mx Spring 2024 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.