Improve code maintainability

Project-02-03/triplalex.py

@@ -0,0 +1,92 @@
+# ------------------------------------------------------------
+# Tokenizer for the TRIPLA parser
+# ------------------------------------------------------------
+
+import ply.lex as lex
+
+reserved = {
+    'let': 'LET',
+    'in': 'IN',
+    'if': 'IF',
+    'then': 'THEN',
+    'else': 'ELSE',
+    'while': 'WHILE',
+    'do': 'DO',
+    'true': 'TRUE',
+    'false': 'FALSE'
+}
+
+# List of token names.
+tokens = [
+    'ID',
+    'CONST',
+    'AOP',
+    'COMP',
+    'EQOP',
+    'LOP',
+    'ASSIGN',
+    'LPAREN', 'RPAREN',
+    'LBRACE', 'RBRACE',
+    'COMMA',
+    'SEMICOLON',
+] + list(reserved.values())
+
+# Simple tokens
+t_LPAREN = r'\('
+t_RPAREN = r'\)'
+t_LBRACE = r'\{'
+t_RBRACE = r'\}'
+t_COMMA = r','
+t_SEMICOLON = r';'
+t_ASSIGN = r'='
+
+# Arithmetic operators
+t_AOP = r'\+|\-|\*|/'
+
+# Comparison operators
+t_COMP = r'<=|>=|<|>'
+
+# Equality operators
+t_EQOP = r'\|\||&&|==|!='
+
+# Logical operators
+t_LOP = r'\|\||&&'
+
+# IDs
+def t_ID(t):
+    r'[A-Za-z_][A-Za-z0-9_]*'
+    t.type = reserved.get(t.value, 'ID')
+    return t
+
+# Constants
+def t_CONST(t):
+    r'0|[1-9][0-9]*'
+    t.value = int(t.value)
+    return t
+
+# Linebreaks
+def t_newline(t):
+    r'\n+'
+    t.lexer.lineno += len(t.value)
+
+# Ignore whitespace
+t_ignore  = ' \t'
+
+# Single-line comment
+def t_comment_single(t):
+    r'//.*'
+    pass
+
+# Multi-line comment
+def t_comment_multi(t):
+    r'/\*([^*]|\*+[^*/])*\*/'
+    t.lexer.lineno += t.value.count('\n')
+    pass
+
+# Error handling
+def t_error(t):
+    print("Illegal character '%s'" % t.value[0])
+    t.lexer.skip(1)
+
+# Build the lexer
+lexer = lex.lex()