1 files changed, 211 insertions, 0 deletions
diff --git a/gerbonara/aperture_macros/expression.py b/gerbonara/aperture_macros/expression.py
new file mode 100644
index 0000000..0cf055a
--- /dev/null
+++ b/gerbonara/aperture_macros/expression.py
@@ -0,0 +1,211 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Copyright 2021 Jan Götte <gerbonara@jaseg.de>
+
+import operator
+import re
+import ast
+
+from ..utils import MM, Inch, MILLIMETERS_PER_INCH
+
+
+def expr(obj):
+    return obj if isinstance(obj, Expression) else ConstantExpression(obj)
+
+
+class Expression:
+    def optimized(self, variable_binding={}):
+        return self
+
+    def __str__(self):
+        return f'<{self.to_gerber()}>'
+
+    def __repr__(self):
+        return f'<E {self.to_gerber()}>'
+
+    def converted(self, unit):
+        return self
+
+    def calculate(self, variable_binding={}, unit=None):
+        expr = self.converted(unit).optimized(variable_binding)
+        if not isinstance(expr, ConstantExpression):
+            raise IndexError(f'Cannot fully resolve expression due to unresolved variables: {expr} with variables {variable_binding}')
+        return expr.value
+
+    def __add__(self, other):
+        return OperatorExpression(operator.add, self, expr(other)).optimized()
+
+    def __radd__(self, other):
+        return expr(other) + self
+
+    def __sub__(self, other):
+        return OperatorExpression(operator.sub, self, expr(other)).optimized()
+
+    def __rsub__(self, other):
+        return expr(other) - self
+
+    def __mul__(self, other):
+        return OperatorExpression(operator.mul, self, expr(other)).optimized()
+
+    def __rmul__(self, other):
+        return expr(other) * self
+
+    def __truediv__(self, other):
+        return OperatorExpression(operator.truediv, self, expr(other)).optimized()
+
+    def __rtruediv__(self, other):
+        return expr(other) / self
+
+    def __neg__(self):
+        return 0 - self
+
+    def __pos__(self):
+        return self
+
+class UnitExpression(Expression):
+    def __init__(self, expr, unit):
+        self._expr = expr
+        self.unit = unit
+
+    def to_gerber(self, unit=None):
+        return self.converted(unit).optimized().to_gerber()
+
+    def __eq__(self, other):
+        return type(other) == type(self) and \
+            self.unit == other.unit and\
+            self._expr == other._expr
+
+    def __str__(self):
+        return f'<{self._expr.to_gerber()} {self.unit}>'
+
+    def __repr__(self):
+        return f'<UE {self._expr.to_gerber()} {self.unit}>'
+
+    def converted(self, unit):
+        if self.unit is None or unit is None or self.unit == unit:
+            return self._expr
+
+        elif MM == unit:
+            return self._expr * MILLIMETERS_PER_INCH
+
+        elif Inch == unit:
+            return self._expr / MILLIMETERS_PER_INCH
+
+        else:
+            raise ValueError(f'invalid unit {unit}, must be "inch" or "mm".')
+
+    def __add__(self, other):
+        if not isinstance(other, UnitExpression):
+            raise ValueError('Unit mismatch: Can only add/subtract UnitExpression from UnitExpression, not scalar.')
+
+        if self.unit == other.unit or self.unit is None or other.unit is None:
+            return UnitExpression(self._expr + other._expr, self.unit)
+
+        if other.unit == 'mm': # -> and self.unit == 'inch'
+            return UnitExpression(self._expr + (other._expr / MILLIMETERS_PER_INCH), self.unit)
+        else: # other.unit == 'inch' and self.unit == 'mm'
+            return UnitExpression(self._expr + (other._expr * MILLIMETERS_PER_INCH), self.unit)
+
+    def __radd__(self, other):
+        # left hand side cannot have been an UnitExpression or __radd__ would not have been called
+        raise ValueError('Unit mismatch: Can only add/subtract UnitExpression from UnitExpression, not scalar.')
+
+    def __sub__(self, other):
+        return (self + (-other)).optimize()
+
+    def __rsub__(self, other):
+        # see __radd__ above
+        raise ValueError('Unit mismatch: Can only add/subtract UnitExpression from UnitExpression, not scalar.')
+
+    def __mul__(self, other):
+        return UnitExpression(self._expr * other, self.unit)
+
+    def __rmul__(self, other):
+        return UnitExpression(other * self._expr, self.unit)
+
+    def __truediv__(self, other):
+        return UnitExpression(self._expr / other, self.unit)
+
+    def __rtruediv__(self, other):
+        return UnitExpression(other / self._expr, self.unit)
+
+    def __neg__(self):
+        return UnitExpression(-self._expr, self.unit)
+
+    def __pos__(self):
+        return self
+
+
+class ConstantExpression(Expression):
+    def __init__(self, value):
+        self.value = value
+
+    def __float__(self):
+        return float(self.value)
+
+    def __eq__(self, other):
+        return type(self) == type(other) and self.value == other.value
+
+    def to_gerber(self, _unit=None):
+        return f'{self.value:.6f}'.rstrip('0').rstrip('.')
+
+    
+class VariableExpression(Expression):
+    def __init__(self, number):
+        self.number = number
+
+    def optimized(self, variable_binding={}):
+        if self.number in variable_binding:
+            return ConstantExpression(variable_binding[self.number])
+        return self
+
+    def __eq__(self, other):
+        return type(self) == type(other) and \
+                self.number == other.number
+
+    def to_gerber(self, _unit=None):
+        return f'${self.number}'
+
+
+class OperatorExpression(Expression):
+    def __init__(self, op, l, r):
+        self.op = op
+        self.l = ConstantExpression(l) if isinstance(l, (int, float)) else l
+        self.r = ConstantExpression(r) if isinstance(r, (int, float)) else r
+
+    def __eq__(self, other):
+        return type(self) == type(other) and \
+                self.op == other.op and \
+                self.l == other.l and \
+                self.r == other.r
+
+    def optimized(self, variable_binding={}):
+        l = self.l.optimized(variable_binding)
+        r = self.r.optimized(variable_binding)
+        
+        if self.op in (operator.add, operator.mul):
+            if id(r) < id(l):
+                l, r = r, l
+
+        if isinstance(l, ConstantExpression) and isinstance(r, ConstantExpression):
+            return ConstantExpression(self.op(float(l), float(r)))
+
+        return OperatorExpression(self.op, l, r)
+        
+    def to_gerber(self, unit=None):
+        lval = self.l.to_gerber(unit)
+        rval = self.r.to_gerber(unit)
+
+        if isinstance(self.l, OperatorExpression):
+            lval = f'({lval})'
+        if isinstance(self.r, OperatorExpression):
+            rval = f'({rval})'
+
+        op = {operator.add: '+',
+              operator.sub: '-',
+              operator.mul: 'X',
+              operator.truediv: '/'} [self.op]
+
+        return f'{lval}{op}{rval}'
+