152 lines
3.9 KiB
Dart
152 lines
3.9 KiB
Dart
import 'dart:math' as Math;
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import 'package:d4rt/d4rt.dart';
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import 'formula_models.dart';
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/// Exception thrown when formula evaluation fails
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class FormulaEvaluationException implements Exception {
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final String message;
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final Object? cause;
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const FormulaEvaluationException(this.message, [this.cause]);
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@override
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String toString() => 'FormulaEvaluationException: $message'
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'${cause != null ? ' (caused by: $cause)' : ''}';
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}
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class MyMath{
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static Number myLog(Number x) => Math.log(x);
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static Number myPow(Number b, Number e) => Math.pow(b,e) as Number;
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}
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class FormulaEvaluator {
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final D4rt _interpreter;
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static D4rt createDefaultInterpreter() => D4rt();
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FormulaEvaluator([D4rt? interpreter]) : _interpreter = interpreter ?? createDefaultInterpreter(){
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prepareInterpreter(_interpreter);
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}
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static Number getNumberValueOf(String s){
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return double.parse(s);
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}
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static void prepareInterpreter(D4rt interpreter){
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final myMathDefinition = BridgedClass(
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nativeType: MyMath,
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name: 'MyMath',
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staticMethods: {
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'myPow': (visitor, positionalArgs, namedArgs) {
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final Number base = getNumberValueOf( positionalArgs[0].toString() );
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final Number exp = getNumberValueOf( positionalArgs[1].toString() );
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return MyMath.myPow(base,exp);
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},
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'myLog': (visitor, positionalArgs, namedArgs) {
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final Number x = getNumberValueOf( positionalArgs[0].toString() );
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return MyMath.myLog(x);
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},
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}
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);
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interpreter.registerBridgedClass(myMathDefinition, "package:d4rt_formulas.dart");
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}
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static dynamic evaluateExpression(String code) {
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final interpreter = createDefaultInterpreter();
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prepareInterpreter(interpreter);
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final d4rtCode = """
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import 'dart:math';
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import "package:d4rt_formulas.dart";
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main()
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{
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return $code;
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}""";
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print("evaluateExpression:\n$d4rtCode");
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final result = interpreter.execute(source: d4rtCode);
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return result.toDouble();
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}
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dynamic evaluate(Formula formula, Map<String, dynamic> inputValues) {
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_validateInputValues(formula, inputValues);
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final completeSource = _buildCompleteSource(formula, inputValues);
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final result = _interpreter.execute(source: completeSource);
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return result;
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}
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void _validateInputValues(Formula formula, Map<String, dynamic> inputValues) {
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final missingVars = <String>[];
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for (final inputVar in formula.inputVarNames()) {
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if (!inputValues.containsKey(inputVar)) {
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missingVars.add(inputVar);
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}
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}
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if (missingVars.isNotEmpty) {
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throw FormulaEvaluationException(
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'Missing required input variables for formula "${formula.name}": '
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'${missingVars.join(', ')}',
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);
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}
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}
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String getOutputVariableName(Formula formula) {
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return formula.output.name;
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}
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String getOutputVariableMagnitude(Formula formula) {
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return formula.output.unit;
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}
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List<String> getInputVariableOrder(Formula formula) {
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return formula.inputVarNames()..sort();
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}
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String _buildCompleteSource(Formula formula, Map<String, dynamic> inputValues) {
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final buffer = StringBuffer();
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buffer.writeln("""
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import 'dart:math';
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import "package:d4rt_formulas.dart";
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main()
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{
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"""
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);
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for (final entry in inputValues.entries) {
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final varName = entry.key;
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final value = entry.value;
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if (value is String) {
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final escapedValue = value.replaceAll('"', '\\"');
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buffer.writeln("""
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final $varName = "$escapedValue";
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""");
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} else {
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buffer.writeln("""
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final $varName = $value;
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""");
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}
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}
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buffer.writeln("""
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late var ${getOutputVariableName(formula)};
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${formula.d4rtCode}
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return ${getOutputVariableName(formula)};
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}
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"""
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);
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return buffer.toString();
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}
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}
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