201505 CSE340 Lecture 02
0 likes752 views
This document contains lecture slides for CSE340 - Principles of Programming Languages. It introduces lexical analysis and discusses how it is used to break source code into individual tokens by identifying strings and words. The key steps of lexical analysis are described, including reading the text line by line, grouping characters into strings, and verifying strings as valid words to create a vector of tokens. Regular expressions and deterministic finite automata are also introduced as techniques for defining token rules. Students are assigned to review these topics for lexical analysis in the provided textbook.
201505 CSE340 Lecture 02
- 1. CSE340 - Principles of Programming Languages Lecture 02: Introduction Javier Gonzalez-Sanchez javiergs@asu.edu BYENG M1-38 Office Hours: By appointment
- 2. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 2 Keywords Level Paradigm Language Analysis Lexical Input: Symbols Output: Words Syntax Input: Words Output: Sentences Semantic Input: Sentences Translate or Execute
- 3. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 3 Analysis int x = 5; float y = "hello; String @z = "9.5"; int x = cse340; if ( x > 14) while (5 == 5) if (int a) a = 1; x = x; for ( ; ; ); y = 13.45.0; int me = 99999000001111222000000111111222223443483045830948; while { x != 9} (); int {x} = 10;
- 4. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 4 High-Level Languages X,E,G,O,O #e1,I,I,0,7 @ OPR 19, AX STO x, AX LIT 5, AX OPR 21, AX LOD #e1,AX CAL 1, AX OPR 0, AX 5 Virtual Machine (interpreter) // sorce code int x; int foo () { read (x); print (5); } main () { foo (); } Lexer Parser Semantic Analyzer Code Generation 01001010101000010 01010100101010010 10100100000011011 11010010110101111 00010010101010010 10101001010101011 Assembler compilation execution
- 5. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 5 Keywords Lexical Alphabet Symbol String Word Token
- 6. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 6 Lexical Analysis int x = 5; float y = "hello; String @z = "9.5"; int x = cse340; if ( x > 14) while (5 == 5) if (int a) a = 1; x = x; for ( ; ; ); y = 13.45.0; int me = 99999000001111222000000111111222223443483045830948; while { x != 9} (); int {x} = 10;
- 7. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 7 Lexical Analysis | Steps a) Read a text FILE line by line b) For each LINE: • Read character by character. • Create sets of consecutive characters (STRING). Try to group the bigger amount of characters as possible. • Start a new set each time that you need. Take care of: Whitespace, Delimiter, Operator, End of Line and others special characters. c) For each STRING: verify if it is a valid WORD. d) Create a VECTOR and store the STRINGs and WORDs.
- 8. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 8 Lexical Analysis int x = 5; float y = "hello; String@z="9.5”;intx=cse340;if(x> 14) while (5 == 5) if (int a) a = 1; x = x; for ( ; ; );y = 13.45.0;int me =99999000001111222000000111111222 223443483045830948;while { x != 9} ();int {x} = 10;
- 9. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 9 Lexical Analysis int x = 5; float y = "hello; String@z="9.5”;intx=cse340;if(x> 14) while (5 == 5) if (int a) a = 1; x = x; for ( ; ; );y = 13.45.0;int me =99999000001111222000000111111222 223443483045830948;while { x != 9} ();int {x} = 10; ”hello "world" bye" # of STRINGS 9 12 3 18 12 2 6 12 3
- 10. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 10 Keywords Lexical Alphabet Symbol String Word Token Rules Regular Expression Deterministic Finite Automata
- 11. Javier Gonzalez-Sanchez | CSE340 | Summer 2015 | 11 Homework Review the following topics: Regular Expressions (Text Book: Chapter 6) and Deterministic Finite Automata
- 12. 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.