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package moe.nea.lisp
class LispExecutionContext() {
private val errorReporter = LispErrorReporter()
val rootStackFrame = StackFrame(null)
fun reportError(name: String, position: HasLispPosition): LispData.LispNil {
println("Error: $name ${position.position}")
return LispData.LispNil
}
fun genBindings(): StackFrame {
return StackFrame(rootStackFrame)
}
fun setupStandardBindings() {
CoreBindings.offerAllTo(rootStackFrame)
Builtins.loadBuiltins(this, rootStackFrame::setValueLocal)
}
fun executeProgram(stackFrame: StackFrame, program: LispAst.Program): LispData? {
var lastValue: LispData? = null
for (node in program.nodes) {
lastValue = executeLisp(stackFrame, node)
}
return lastValue
}
fun executeLisp(stackFrame: StackFrame, node: LispAst.LispNode): LispData {
when (node) {
is LispAst.Parenthesis -> {
val first = node.items.firstOrNull()
?: return reportError("Cannot execute empty parenthesis ()", node)
val rest = node.items.drop(1)
return when (val resolvedValue = resolveValue(stackFrame, first)) {
is LispData.LispExecutable -> {
resolvedValue.execute(this, node, stackFrame, rest)
}
else -> reportError("Cannot evaluate expression of type $resolvedValue", node)
}
}
else -> return reportError("Expected invocation", node)
}
}
fun resolveValue(stackFrame: StackFrame, node: LispAst.LispNode): LispData {
return when (node) {
is LispAst.Atom -> LispData.Atom(node.label)
is LispAst.Parenthesis -> executeLisp(stackFrame, node)
is LispAst.Reference -> stackFrame.resolveReference(node.label)
?: reportError("Could not resolve variable ${node.label}", node)
is LispAst.NumberLiteral -> LispData.LispNumber(node.numberValue)
is LispAst.StringLiteral -> LispData.LispString(node.parsedString)
}
}
}
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