bb87928bce
Upstream: https://github.com/Rhoban/onshape-to-robot Upstream-Commit: 80e710700aac9573a2230f74f7ce9e094833a0bc Upstream-Branch: master
120 lines
3.4 KiB
Python
120 lines
3.4 KiB
Python
import numpy as np
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import ast
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import operator as op
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class ExpressionParser:
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"""
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Evaluate Onshape expression
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See https://cad.onshape.com/help/Content/numeric-fields.htm
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This parser is based on ast module.
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"""
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def __init__(self):
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self.variables_lazy_loading = None
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self.variables = {
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"pi": np.pi, "Pi": np.pi, "PI": np.pi
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}
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# Supported operators
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operators = {
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ast.Add: op.add,
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ast.Sub: op.sub,
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ast.Mult: op.mul,
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ast.Div: op.truediv,
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ast.Pow: op.pow,
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ast.BitXor: op.xor,
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ast.USub: op.neg,
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ast.Mod: op.mod,
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}
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# Supporter functions
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functions = {
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"cos": np.cos,
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"sin": np.sin,
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"tan": np.tan,
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"acos": np.arccos,
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"asin": np.arcsin,
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"atan": np.arctan,
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"atan2": np.arctan2,
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"cosh": np.cosh,
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"sinh": np.sinh,
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"tanh": np.tanh,
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"asinh": np.arcsinh,
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"acosh": np.arccosh,
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"atanh": np.arctanh,
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"ceil": np.ceil,
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"floor": np.floor,
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"round": np.round,
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"exp": np.exp,
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"sqrt": np.sqrt,
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"abs": np.abs,
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"max": np.max,
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"min": np.min,
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"log": np.log,
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"log10": np.log10,
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}
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def eval_expr(self, expr):
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# Length units. Converting everything to meter / radian
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units = {
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"millimeter": 1e-3,
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"mm": 1e-3,
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"centimeter": 1e-2,
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"cm": 1e-2,
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"meter": 1.0,
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"inch": 0.0254,
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"in": 0.0254,
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"foot": 0.3048,
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"ft": 0.3048,
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"yard": 0.9144,
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"yd": 0.9144,
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"radian": 1.0,
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"rad": 1.0,
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"degree": np.pi / 180,
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"deg": np.pi / 180,
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"m": 1.0
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}
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for unit, factor in units.items():
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expr = expr.replace(f" {unit}", f"*{factor}")
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expr = expr.replace("#", "")
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expr = expr.replace("^", "**")
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return self.eval_(ast.parse(expr, mode="eval").body)
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def eval_(self, node):
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if isinstance(node, ast.Constant):
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return float(node.value)
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elif isinstance(node, ast.BinOp):
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return self.operators[type(node.op)](
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self.eval_(node.left), self.eval_(node.right)
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)
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elif isinstance(node, ast.UnaryOp): # e.g., -1
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return self.operators[type(node.op)](self.eval_(node.operand))
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elif isinstance(node, ast.Name):
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if (
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node.id not in self.variables
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and self.variables_lazy_loading is not None
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):
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self.variables_lazy_loading()
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self.variables_lazy_loading = None
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if node.id not in self.variables:
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raise ValueError(f"Unknown variable in expression: {node.id}")
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return self.variables[node.id]
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elif isinstance(node, ast.Call):
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if node.func.id not in self.functions:
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raise ValueError(f"Unknown function in expression: {node.func.id}")
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return self.functions[node.func.id](*[self.eval_(arg) for arg in node.args])
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else:
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raise TypeError(node)
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if __name__ == "__main__":
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ep = ExpressionParser()
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ep.variables["x"] = 5
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print(ep.eval_expr("(cos(5 deg)) mm + #x inch"))
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print(ep.eval_expr("-sin(3/(2^2) deg)"))
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