diff --git a/PythonicGCodeMachine/GCode/Lexer.py b/PythonicGCodeMachine/GCode/Lexer.py
new file mode 100644
index 0000000000000000000000000000000000000000..b6202a5ba35b43d5838fbc1397ea7fb4aa69fae4
--- /dev/null
+++ b/PythonicGCodeMachine/GCode/Lexer.py
@@ -0,0 +1,219 @@
+####################################################################################################
+#
+# PythonicGCodeMachine - @licence_header_description@
+# Copyright (C) 2018 Fabrice Salvaire
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+####################################################################################################
+
+####################################################################################################
+
+import re
+
+import PythonicGCodeMachine.Lexer as lexer
+
+####################################################################################################
+
+class GCodeLexerError(ValueError):
+    pass
+
+####################################################################################################
+
+class GCodeLexer:
+
+    """Class to implement a CGode lexer.
+
+    For references, see
+
+    * The NIST RS274NGC Interpreter — Version 3 — Appendix E. Production Rules for the RS274/NGC Language
+    * http://linuxcnc.org/docs/2.7/html/gcode/overview.html
+
+    """
+
+    # List of token names.
+    tokens = (
+        'ABSOLUTE_VALUE',
+        'AND',
+        'ARC_COSINE',
+        'ARC_SINE',
+        'ARC_TANGENT',
+        'COSINE',
+        'DECIMAL_POINT',
+        'DIVIDED_BY',
+        'EQUAL_SIGN',
+        'EXCLUSIVE_OR',
+        'E_RAISED_TO',
+        'FIX_DOWN',
+        'FIX_UP',
+        'LEFT_BRACKET',
+        'LEFT_PARENTHESIS',
+        'MINUS',
+        'MODULO',
+        'NATURAL_LOG_OF',
+        'NON_EXCLUSIVE_OR',
+        'PARAMETER_SIGN',
+        'PLUS',
+        'POWER',
+        'RIGHT_BRACKET',
+        'RIGHT_PARENTHESIS',
+        'ROUND',
+        'SINE',
+        'SQUARE_ROOT',
+        'TANGENT',
+        'TIMES',
+
+        'A', 'B', 'C', 'D',
+        'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
+        'P', 'Q', 'R', 'S', 'T',
+        'X', 'Y', 'Z',
+
+        'POSITIVE_INTEGER',
+        'POSITIVE_REAL',
+        'REAL',
+        'INLINE_COMMENT',
+        'EOF_COMMENT',
+    )
+
+    # Regular expression rules for simple tokens
+    t_ABSOLUTE_VALUE = r'abs'
+    t_AND = r'and'
+    t_ARC_COSINE = r'acos'
+    t_ARC_SINE = r'asin'
+    t_ARC_TANGENT = r'atan'
+    # t_BLOCK_DELETE = r'\/'
+    t_COSINE = r'cos'
+    t_DECIMAL_POINT = r'\.'
+    t_DIVIDED_BY = r'\/'
+    t_EQUAL_SIGN = r'='
+    t_EXCLUSIVE_OR = r'xor'
+    t_E_RAISED_TO = r'exp'
+    t_FIX_DOWN = r'fix'
+    t_FIX_UP = r'fup'
+    t_LEFT_BRACKET = r'\['
+    t_LEFT_PARENTHESIS = r'\('
+    t_MINUS = r'-'
+    t_MODULO = r'mod'
+    t_NATURAL_LOG_OF = r'ln'
+    t_NON_EXCLUSIVE_OR = r'or'
+    t_PARAMETER_SIGN = r'\#'
+    t_PLUS = r'\+'
+    t_POWER = r'\*\*'
+    t_RIGHT_BRACKET = r'\]'
+    t_RIGHT_PARENTHESIS = r'\)'
+    t_ROUND = r'round'
+    t_SINE = r'sin'
+    t_SQUARE_ROOT = r'sqrt'
+    t_TANGENT = r'tan'
+    t_TIMES = r'\*'
+
+    t_A = r'a'
+    T_B = r'b'
+    t_C = r'c'
+    t_D = r'd'
+
+    t_F = r'f'
+    t_G = r'g'
+    t_H = r'h'
+    t_I = r'i'
+    t_J = r'j'
+    t_K = r'k'
+    t_L = r'l'
+    t_M = r'm'
+    t_N = r'n'
+
+    t_P = r'p'
+    t_Q = r'q'
+    t_R = r'r'
+    t_S = r's'
+    t_T = r't'
+
+    t_X = r'x'
+    t_Y = r'y'
+    t_Z = r'z'
+
+    # def t_POSITIVE_INTEGER(self, t):
+    #     r'\d+'
+    #     t.value = int(t.value)
+    #     return t
+
+    # def t_POSITIVE_REAL(self, t):
+    #     r'\d*\.\d+'
+    #     t.value = float(t.value)
+    #     return t
+
+    def t_REAL(self, t):
+        # r'((-)?((\d*\.\d+)(E[\+-]?\d+)?|([1-9]\d*E[\+-]?\d+)))'
+        r'((-)?\d*(\.)?\d+)'
+        value = t.value
+        if '.' in value:
+            value = float(value)
+            if value > 0:
+                t.type = 'POSITIVE_REAL'
+            else:
+                t.type = 'REAL'
+        else:
+            value = int(value)
+            t.type = 'POSITIVE_INTEGER'
+        t.value = value
+        return t
+
+    def t_INLINE_COMMENT(self, t):
+        r'\([^\)]*\)'
+        value = t.value[1:-1]
+        position = value.find('(')
+        if position != -1:
+            raise GCodeLexerError(t.lexpos + position +1)
+        t.value = value
+        return t
+
+    def t_EOF_COMMENT(self, t):
+        r';.*'
+        t.value = t.value[1:]
+        return t
+
+    # Ignored characters (spaces and tabs)
+    t_ignore  = ' \t'
+
+    def t_error(self, t):
+        'Error handling rule'
+        # t.lexer.skip(1)
+        # raise GCodeLexerError("Illegal character @{} '{}'".format(t.lexpos, t.value))
+        raise GCodeLexerError(t.lexpos)
+
+    ##############################################
+
+    def __init__(self):
+        self._build()
+
+    ##############################################
+
+    def _build(self, **kwargs):
+        """Build the lexer"""
+        self._lexer = lexer.lex(
+            module=self,
+            reflags=int(re.VERBOSE + re.IGNORECASE),
+            **kwargs,
+        )
+
+    ##############################################
+
+    def tokenize(self, data):
+
+        self._lexer.input(data)
+        while True:
+            token = self._lexer.token()
+            if not token:
+                break
+            yield token
diff --git a/PythonicGCodeMachine/__init__.py b/PythonicGCodeMachine/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391