private static void DoDeconstruct(LNode arg, IMacroContext context, bool printErrorOnFailure)
{
LNode patternSpec = arg.Args[0, LNode.Missing], input = arg.Args[1, LNode.Missing];
if (!arg.Calls(S.Assign, 2))
{
if (arg.Calls(S.Lambda, 2))
{
G.Swap(ref patternSpec, ref input);
}
else
{
context.Sink.Error(arg, "expected an assignment (`patterns = input`)");
return;
}
}
// Build list of patterns out of the binary operator series p1 | p2 | p3
var patterns = new FVList <LNode>();
while (patternSpec.Calls(S.OrBits, 2) && !patternSpec.IsParenthesizedExpr())
{
patterns.Add(patternSpec[1]);
patternSpec = patternSpec[0];
}
patterns.Add(patternSpec);
// Remove outer braces, then run macros
patterns = patterns.SmartSelect(p => p.Calls(S.Braces, 1) ? p[0] : p);
input = input.Calls(S.Braces, 1) ? input[0] : input;
input = context.PreProcess(input);
// Perform matching & capturing
foreach (var pattern in patterns)
{
IDictionary <Symbol, LNode> captures;
if (LNodeExt.MatchesPattern(input, pattern, out captures))
{
if (captures.Count == 0)
{
context.Write(printErrorOnFailure ? Severity.Warning : Severity.Error, pattern,
"This pattern has no effect, since it does not use `$` to capture any variables.");
}
SetSyntaxVariables(captures, context);
return;
}
}
if (printErrorOnFailure)
{
context.Sink.Error(arg, "Deconstruction failed.");
}
}
public static bool IsComplexIdentifier(LNode n, ICI f = ICI.Default, Pedantics p = Pedantics.Lax)
{
// Returns true if 'n' is printable as a complex identifier.
//
// To be printable, a complex identifier in EC# must not contain
// attributes ((p & Pedantics.DropNonDeclAttrs) != 0 to override) and must be
// 1. A simple symbol
// 2. A substitution expression
// 3. A dotted expr (a.b), where 'a' is a complex identifier and 'b'
// is (1) or (2); structures like #.(a, b, c) and #.(a, b<c>) do
// not count as complex identifiers. Note that a.b<c> is
// structured #of(#.(a, b), c), not #.(a, #of(b, c)). A dotted
// expression that starts with a dot, such as .a.b, is structured
// (.a).b rather than .(a.b); unary . has high precedence.
// 4. An #of expr a<b,...>, where
// - 'a' is a complex identifier and not itself an #of expr
// - each arg 'b' is a complex identifier (if printing in C# style)
//
// Type names have the same structure, with the following patterns for
// arrays, pointers, nullables and typeof<>:
//
// Foo* <=> #of(@*, Foo)
// Foo[] <=> #of(@`[]`, Foo)
// Foo[,] <=> #of(#`[,]`, Foo)
// Foo? <=> #of(@?, Foo)
// typeof<X> <=> #of(#typeof, X)
//
// Note that we can't just use #of(Nullable, Foo) for Foo? because it
// doesn't work if System is not imported. It's reasonable to allow #?
// as a synonym for global::System.Nullable, since we have special
// symbols for types like #int32 anyway.
//
// (a.b<c>.d<e>.f is structured ((((a.b)<c>).d)<e>).f or #.(#of(#.(#of(#.(a,b), c), d), e), f)
if ((f & ICI.AllowAttrs) == 0 && ((f & ICI.AllowParensAround) != 0 ? HasPAttrs(n, p) : HasPAttrsOrParens(n, p)))
{
// Attribute(s) are illegal, except 'in', 'out' and 'where' when
// TypeParamDefinition inside <...>
return((f & (ICI.NameDefinition | ICI.InOf)) == (ICI.NameDefinition | ICI.InOf) && IsPrintableTypeParam(n));
}
if (n.IsId)
{
return(true);
}
if (CallsWPAIH(n, S.Substitute, 1, p))
{
return(true);
}
if (CallsMinWPAIH(n, S.Of, 1, p) && (f & ICI.DisallowOf) == 0)
{
var baseName = n.Args[0];
if (!IsComplexIdentifier(baseName, (f & (ICI.DisallowDotted)) | ICI.DisallowOf, p))
{
return(false);
}
if ((f & ICI.AllowAnyExprInOf) != 0)
{
return(true);
}
return(OfHasNormalArgs(n, (f & ICI.NameDefinition) != 0, p));
}
if (CallsWPAIH(n, S.Dot, p) && (f & ICI.DisallowDotted) == 0 && Range.IsInRange(n.ArgCount, 1, 2))
{
var args = n.Args;
LNode lhs = args[0], rhs = args.Last;
// right-hand argument must be simple
var rhsFlags = (f & ICI.ExprMode) | ICI.DisallowOf | ICI.DisallowDotted;
if ((f & ICI.ExprMode) != 0)
{
rhsFlags |= ICI.AllowParensAround;
}
if (!IsComplexIdentifier(args.Last, rhsFlags, p))
{
return(false);
}
if ((f & ICI.ExprMode) != 0 && lhs.IsParenthesizedExpr() || (lhs.IsCall && !lhs.Calls(S.Dot) && !lhs.Calls(S.Of)))
{
return(true);
}
return(IsComplexIdentifier(args[0], (f & ICI.ExprMode), p));
}
return(false);
}
public bool AutoPrintComplexIdentOperator(Precedence precedence, Precedence context, Ambiguity flags)
{
// Handles #of and @`.`, including array types
int argCount = _n.ArgCount;
Symbol name = _n.Name;
Debug.Assert((name == S.Of || name == S.Dot) && _n.IsCall);
var first = _n.Args[0, null];
if (first == null)
{
return(false); // no args
}
bool needParens, needSpecialOfNotation = false;
if (!CanAppearIn(precedence, context, out needParens) || needParens)
{
return(false); // this only happens inside $ operator, e.g. $(a.b)
}
if (name == S.Dot)
{
// The trouble with the dot is its high precedence; because of
// this, arguments after a dot cannot use prefix notation as a
// fallback. For example "@.(a, b(c))" cannot be printed "a.b(c)"
// since that means @.(a, b)(c)". The first argument to non-
// unary "." can use prefix notation safely though, e.g.
// "@.(b(c), a)" can (and must) be printed "b(c).a".
if (argCount > 2)
{
return(false);
}
if (HasPAttrs(first))
{
return(false);
}
LNode afterDot = _n.Args.Last;
// Unary dot is no problem: .(a) is parsed the same as .a, i.e.
// the parenthesis are ignored, so we can print an expr like
// @`.`(a+b) as .(a+b), but the parser counts parens on binary
// dot, so in that case the argument after the dot must not be any
// kind of call (except substitution) and must not have attributes,
// unless it is in parens.
if (argCount == 2 && !afterDot.IsParenthesizedExpr())
{
if (HasPAttrs(afterDot))
{
return(false);
}
if (afterDot.IsCall && afterDot.Name != S.Substitute)
{
return(false);
}
}
else if ((flags & Ambiguity.CastRhs) != 0)
{
return(false); // cannot print (Foo) @`.`(x) as (Foo) .x
}
}
else if (name == S.Of)
{
var ici = ICI.Default | ICI.AllowAttrs;
if ((flags & Ambiguity.InDefinitionName) != 0)
{
ici |= ICI.NameDefinition;
}
if (!IsComplexIdentifier(_n, ici))
{
if (IsComplexIdentifier(_n, ici | ICI.AllowAnyExprInOf))
{
needSpecialOfNotation = true;
}
else
{
return(false);
}
}
}
if (name == S.Dot)
{
if (argCount == 1)
{
_out.Write('.', true);
PrintExpr(first, EP.Substitute);
}
else
{
PrintExpr(first, precedence.LeftContext(context), flags & Ambiguity.TypeContext);
_out.Write('.', true);
PrintExpr(_n.Args[1], precedence.RightContext(context));
}
}
else if (_n.Name == S.Of)
{
// Check for special type names such as Foo? or Foo[]
Symbol stk = SpecialTypeKind(_n, flags, context);
if (stk != null)
{
if (S.IsArrayKeyword(stk))
{
// We do something very strange in case of arrays of arrays:
// the order of the square brackets must be reversed when
// arrays are nested. For example, an array of two-dimensional
// arrays of int is written int[][,], rather than int[,][]
// which would be much easier to handle.
var stack = InternalList <Symbol> .Empty;
var innerType = _n;
do
{
stack.Add(stk);
innerType = innerType.Args[1];
} while (S.IsArrayKeyword(stk = SpecialTypeKind(innerType, flags, context) ?? GSymbol.Empty));
PrintType(innerType, EP.Primary.LeftContext(context), (flags & Ambiguity.AllowPointer));
for (int i = 0; i < stack.Count; i++)
{
_out.Write(stack[i].Name, true); // e.g. [] or [,]
}
}
else
{
PrintType(_n.Args[1], EP.Primary.LeftContext(context), (flags & Ambiguity.AllowPointer));
_out.Write(stk == S._Pointer ? '*' : '?', true);
}
return(true);
}
PrintExpr(first, precedence.LeftContext(context));
_out.Write(needSpecialOfNotation ? "!(" : "<", true);
for (int i = 1; i < argCount; i++)
{
if (i > 1)
{
WriteThenSpace(',', SpaceOpt.AfterCommaInOf);
}
PrintType(_n.Args[i], StartExpr, Ambiguity.InOf | Ambiguity.AllowPointer | (flags & Ambiguity.InDefinitionName));
}
_out.Write(needSpecialOfNotation ? ')' : '>', true);
}
else
{
Debug.Assert(_n.Name == S.Substitute);
G.Verify(AutoPrintOperator(ContinueExpr, 0));
}
return(true);
}
