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Diffstat (limited to 'calculator-java/src/main/java/ch/bfh/CalculatorLexer.java')
-rw-r--r--calculator-java/src/main/java/ch/bfh/CalculatorLexer.java106
1 files changed, 0 insertions, 106 deletions
diff --git a/calculator-java/src/main/java/ch/bfh/CalculatorLexer.java b/calculator-java/src/main/java/ch/bfh/CalculatorLexer.java
deleted file mode 100644
index 48d009e..0000000
--- a/calculator-java/src/main/java/ch/bfh/CalculatorLexer.java
+++ /dev/null
@@ -1,106 +0,0 @@
-package ch.bfh;
-import ch.bfh.exceptions.LexerException;
-
-// Lexer for classical arithmetic expressions with identifiers and assignments.
-// Scans a source string char by char.
-
-public class CalculatorLexer {
-
- private String src; // source string for lexical analysis
- private int idx; // current index in source
- private int len; // length of source
-
- public CalculatorLexer() { }
-
- public void initLexer(String source) {
- this.src = source;
- idx = 0;
- len = src.length();
- }
-
- // Consumes letters only and builds an identifier
- private String identifier() {
- StringBuffer s = new StringBuffer();
-
- do {
- s.append(src.charAt(idx));
- idx++;
- } while (idx < len && Character.isLetter(src.charAt(idx)));
- return s.toString();
- }
-
- // Consumes digits and convert integer part and decimal part
- // Convert characters using the formula
- // "3456.253" = [(((3+0)*10+4)*10+5)*10+6]+[0.1*2+0.01*5+0.001*3]
- private double number() throws LexerException {
- double v = 0; // accumulates the result
- double factor = 0.1; // factor for decimal part
-
- do { // integer part
- v = v * 10 + Character.digit(src.charAt(idx),30);
- idx++;
- } while (idx < len && Character.isDigit(src.charAt(idx)));
- if (idx < len && src.charAt(idx) == '.') { // decimal point
- idx++;
- if (idx < len && Character.isDigit(src.charAt(idx))) { // decimal part
- while (idx < len && Character.isDigit(src.charAt(idx))) {
- v = v + (factor * Character.digit(src.charAt(idx),30));
- factor = factor * 0.1;
- idx++;
- }
- }
- else throw new LexerException("Illegal number: decimal part missing");
- }
- return v;
- }
-
- // Skips blanks, tabs, newlines
- private void skip() {
- char c;
- while (idx < len) {
- c = src.charAt(idx);
- if (c==' ' || c=='\t' || c=='\n') idx++;
- else break;
- }
- }
-
- // returns next token
- public Token nextToken() throws LexerException {
- Token tok = new Token();
-
- skip();
- if (idx>=len) {
- tok.str="EOL";
- tok.type=Token.EOL;
- }
- else
- // is it a positive number?
- if (Character.isDigit(src.charAt(idx))) {
- tok.value = number();
- tok.type = Token.NUM;
- tok.str = Double.toString(tok.value);
- }
- else
- if (Character.isLetter(src.charAt(idx))) {
- tok.value = 0;
- tok.type = Token.ID;
- tok.str = identifier();
- if (tok.str.compareTo("let")==0) tok.type = Token.LET;
- if (tok.str.compareTo("exit")==0) tok.type = Token.END;
- }
- else {
- switch (src.charAt(idx)) {
- case '+': tok.type = Token.ADD; tok.str = "+"; break;
- case '-': tok.type = Token.SUB; tok.str = "-"; break;
- case '*': tok.type = Token.MUL; tok.str = "*"; break;
- case '/': tok.type = Token.DIV; tok.str = "/"; break;
- case '(': tok.type = Token.PAL; tok.str = "("; break;
- case ')': tok.type = Token.PAR; tok.str = ")"; break;
- case '=': tok.type = Token.EQU; tok.str = "="; break;
- default : throw new LexerException("Illegal Token: '" + src.charAt(idx) + "'");
- }
- idx++;
- }
- return tok;
- }
-} \ No newline at end of file