private static void FromSetExpression(ChainBuilder chain, object[] expression, string sourceFile, int lineNumber)
{
if (expression.Length < 4 || !expression[2].Equals("=") || !(expression[1] is string name))
{
throw new SyntaxError(
$"A set command has the format [set name = value], which doesn't match the expression {Writer.TermToString(expression)}.",
sourceFile, lineNumber);
}
if (DefinitionStream.IsGlobalVariableName(name))
{
chain.AddStep(new AssignmentStep(StateVariableName.Named(name),
FunctionalExpressionParser.FromTuple(chain.CanonicalizeArglist(expression), 3, sourceFile,
lineNumber),
null));
}
else if (DefinitionStream.IsLocalVariableName(name))
{
chain.AddStep(new AssignmentStep(chain.GetLocal(name),
FunctionalExpressionParser.FromTuple(chain.CanonicalizeArglist(expression), 3, sourceFile,
lineNumber),
null));
}
else
{
throw new SyntaxError(
$"A set command can only update a variable; it can't update {expression[1]}",
sourceFile, lineNumber);
}
}
private static void FromIncDecExpression(ChainBuilder chain, object[] expression, string sourceFile, int lineNumber)
{
if (expression.Length < 2 || !(expression[1] is string name))
{
throw new SyntaxError(
$"An inc or dec command has the format [inc name] or [inc name amount], which doesn't match the expression {Writer.TermToString(expression)}.",
sourceFile, lineNumber);
}
var operation = expression[0].Equals("inc") ? "+" : "-";
var increment = (expression.Length == 2) ? new object[] { 1 } : expression.Skip(2).Prepend("(").Append(")");
var newValueExpression = new object[]
{
name,
operation
}.Concat(increment).ToArray();
if (DefinitionStream.IsGlobalVariableName(name))
{
chain.AddStep(new AssignmentStep(StateVariableName.Named(name),
FunctionalExpressionParser.FromTuple(chain.CanonicalizeArglist(newValueExpression), 0, sourceFile,
lineNumber),
null));
}
else if (DefinitionStream.IsLocalVariableName(name))
{
throw new SyntaxError(
$"An inc or dec command cannot be used with the local variable {name} because local variables can only be set once.",
sourceFile, lineNumber);
}
else
{
throw new SyntaxError(
$"An inc or dec command can only update a variable; it can't update {expression[1]}",
sourceFile, lineNumber);
}
}