public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList <LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces))
{
contents = node.Args[1].Args;
var outputs = new WList <LNode>();
input = MaybeAddTempVarDecl(context, input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i)
{
var @case = contents[case_i];
if (!IsCaseLabel(@case))
{
return(Reject(context, contents[0], "In 'match': expected 'case' statement"));
}
for (next_i = case_i + 1; next_i < contents.Count; next_i++)
{
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
{
break;
}
if (stmt.Calls(S.Break, 0))
{
next_i++;
break;
}
}
var handler = new VList <LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0)
{
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
{
outputs.Add(codeGen.GenCodeForPattern(pattern));
}
}
else // default:
// Note: the extra {braces} around the handler are rarely
// needed. They are added just in case the handler declares a
// variable and a different handler declares another variable
// by the same name, which is illegal unless we add braces.
{
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
{
context.Sink.Error(contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
}
return(LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false))));
}
}
return(null);
}
[LexicalMacro("match (var) { case ...: ... }; // In LES, use a => b instead of case a: b", "Attempts to match and deconstruct an object against a \"pattern\", such as a tuple or an algebraic data type. Example:\n" + "match (obj) { \n" + " case is Shape(ShapeType.Circle, $size, Location: $p is Point<int>($x, $y)): \n" + " Circle(size, x, y); \n" + "}\n\n" + "This is translated to the following C# code: \n" + "do { \n" + " Point<int> p; \n" + " Shape tmp1; \n" + " if (obj is Shape) { \n" + " var tmp1 = (Shape)obj; \n" + " if (tmp1.Item1 == ShapeType.Circle) { \n" + " var size = tmp1.Item2; \n" + " var tmp2 = tmp1.Location; \n" + " if (tmp2 is Point<int>) { \n" + " var p = (Point<int>)tmp2; \n" + " var x = p.Item1; \n" + " var y = p.Item2; \n" + " Circle(size, x, y); \n" + " break; \n" + " } \n" + " }\n" + " }\n" + "} while(false); \n" + "`break` is not expected at the end of each handler (`case` code block), but it can " + "be used to exit early from a `case`. You can associate multiple patterns with the same " + "handler using `case pattern1, pattern2:` in EC#, but please note that (due to a " + "limitation of plain C#) this causes code duplication since the handler will be repeated " + "for each pattern.")] public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList <LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces))
{
contents = node.Args[1].Args;
var outputs = new WList <LNode>();
input = MaybeAddTempVarDecl(input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i)
{
var @case = contents[case_i];
if (!IsCaseLabel(@case))
{
return(Reject(context, contents[0], "In 'match': expected 'case' statement"));
}
for (next_i = case_i + 1; next_i < contents.Count; next_i++)
{
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
{
break;
}
if (stmt.Calls(S.Break, 0))
{
next_i++;
break;
}
}
var handler = new VList <LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0)
{
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
{
outputs.Add(codeGen.GenCodeForPattern(pattern));
}
}
else
{
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
{
context.Write(Severity.Error, contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
}
return(LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false))));
}
}
return(null);
}
public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList <LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces))
{
contents = node.Args[1].Args;
var outputs = new WList <LNode>();
input = MaybeAddTempVarDecl(context, input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i)
{
var @case = contents[case_i];
if (!IsCaseLabel(@case))
{
return(Reject(context, contents[0], "In 'match': expected 'case' statement"));
}
for (next_i = case_i + 1; next_i < contents.Count; next_i++)
{
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
{
break;
}
if (stmt.Calls(S.Break, 0))
{
next_i++;
break;
}
}
var handler = new VList <LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0)
{
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
{
outputs.Add(codeGen.GenCodeForPattern(pattern));
}
}
else
{
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
{
context.Write(Severity.Error, contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
}
return(LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false))));
}
}
return(null);
}
public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList<LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces)) {
contents = node.Args[1].Args;
var outputs = new WList<LNode>();
input = MaybeAddTempVarDecl(context, input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i) {
var @case = contents[case_i];
if (!IsCaseLabel(@case))
return Reject(context, contents[0], "In 'match': expected 'case' statement");
for (next_i = case_i + 1; next_i < contents.Count; next_i++) {
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
break;
if (stmt.Calls(S.Break, 0)) {
next_i++;
break;
}
}
var handler = new VList<LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0) {
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
outputs.Add(codeGen.GenCodeForPattern(pattern));
} else { // default:
// Note: the extra {braces} around the handler are rarely
// needed. They are added just in case the handler declares a
// variable and a different handler declares another variable
// by the same name, which is illegal unless we add braces.
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
context.Sink.Error(contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
return LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false)));
}
}
return null;
}
[LexicalMacro("match (var) { case ...: ... }; // In LES, use a => b instead of case a: b", "Attempts to match and deconstruct an object against a \"pattern\", such as a tuple or an algebraic data type. Example:\n" + "match (obj) { \n" + " case is Shape(ShapeType.Circle, $size, Location: $p is Point<int>($x, $y)): \n" + " Circle(size, x, y); \n" + "}\n\n" + "This is translated to the following C# code: \n" + "do { \n" + " Point<int> p; \n" + " Shape tmp1; \n" + " if (obj is Shape) { \n" + " var tmp1 = (Shape)obj; \n" + " if (tmp1.Item1 == ShapeType.Circle) { \n" + " var size = tmp1.Item2; \n" + " var tmp2 = tmp1.Location; \n" + " if (tmp2 is Point<int>) { \n" + " var p = (Point<int>)tmp2; \n" + " var x = p.Item1; \n" + " var y = p.Item2; \n" + " Circle(size, x, y); \n" + " break; \n" + " } \n" + " }\n" + " }\n" + "} while(false); \n" + "`break` is not expected at the end of each handler (`case` code block), but it can " + "be used to exit early from a `case`. You can associate multiple patterns with the same " + "handler using `case pattern1, pattern2:` in EC#, but please note that (due to a " + "limitation of plain C#) this causes code duplication since the handler will be repeated " + "for each pattern.")] public static LNode match(LNode node, IMacroContext context)
{
{
LNode input;
VList<LNode> contents;
if (node.Args.Count == 2 && (input = node.Args[0]) != null && node.Args[1].Calls(CodeSymbols.Braces)) {
contents = node.Args[1].Args;
var outputs = new WList<LNode>();
input = MaybeAddTempVarDecl(input, outputs);
int next_i = 0;
for (int case_i = 0; case_i < contents.Count; case_i = next_i) {
var @case = contents[case_i];
if (!IsCaseLabel(@case))
return Reject(context, contents[0], "In 'match': expected 'case' statement");
for (next_i = case_i + 1; next_i < contents.Count; next_i++) {
var stmt = contents[next_i];
if (IsCaseLabel(stmt))
break;
if (stmt.Calls(S.Break, 0)) {
next_i++;
break;
}
}
var handler = new VList<LNode>(contents.Slice(case_i + 1, next_i - (case_i + 1)));
if (@case.Calls(S.Case) && @case.Args.Count > 0) {
var codeGen = new CodeGeneratorForMatchCase(context, input, handler);
foreach (var pattern in @case.Args)
outputs.Add(codeGen.GenCodeForPattern(pattern));
} else {
outputs.Add(LNode.Call(CodeSymbols.Braces, LNode.List(handler)).SetStyle(NodeStyle.Statement));
if (next_i < contents.Count)
context.Write(Severity.Error, contents[next_i], "The default branch must be the final branch in a 'match' statement.");
}
}
return LNode.Call(CodeSymbols.DoWhile, LNode.List(outputs.ToVList().AsLNode(S.Braces), LNode.Literal(false)));
}
}
return null;
}