# Try to parse the `string` as something
	#
	# Returns the first possible syntacticaly correct type among:
	#
	# - a type `AType`
	# - a single `Token`
	# - an expression `AExpr`
	# - a block of statements `ABlockExpr`
	# - a full module `AModule`
	# - a `AError` if nothing else matches
	#
	#     var tc = new ToolContext
	#     assert tc.parse_something("foo") isa TId
	#     assert tc.parse_something("foo[bar]") isa AExpr
	#     assert tc.parse_something("Foo[Bar]") isa AType
	#     assert tc.parse_something("foo\nbar") isa ABlockExpr
	#     assert tc.parse_something("fun foo do bar\nfoo") isa AModule
	#     assert tc.parse_something("fun fun") isa AParserError
	#     assert tc.parse_something("?%^&") isa ALexerError
	fun parse_something(string: String): ANode
	do
		var source = new SourceFile.from_string("", string)
		var error
		var tree
		var eof
		var lexer

		lexer = new InjectedLexer(source)
		lexer.injected_before.add new TKwvar
		lexer.injected_before.add new TId
		lexer.injected_before.add new TColumn
		lexer.injected_before.add new TClassid
		lexer.injected_before.add new TObra
		lexer.injected_after.add new TCbra
		tree = (new Parser(lexer)).parse
		eof = tree.n_eof
		if not eof isa AError then
			var ntype = tree.n_base.n_classdefs.first.n_propdefs.first.as(AMethPropdef).n_block.as(ABlockExpr).n_expr.first.as(AVardeclExpr).n_type.n_types.first
			ntype.parent = null
			return ntype
		end
		error = eof

		lexer = new Lexer(source)
		var first = lexer.next
		if first isa EOF then return first
		var second = lexer.next
		if second isa EOF and not second isa AError then
			first.parent = null
			return first
		end

		lexer = new InjectedLexer(source)
		lexer.injected_before.add new TKwvar
		lexer.injected_before.add new TId
		lexer.injected_before.add new TAssign
		lexer.injected_before.add new TOpar
		lexer.injected_after.add new TCpar
		tree = (new Parser(lexer)).parse
		eof = tree.n_eof
		if not eof isa AError then
			var nexpr = tree.n_base.n_classdefs.first.n_propdefs.first.as(AMethPropdef).n_block.as(ABlockExpr).n_expr.first.as(AVardeclExpr).n_expr.as(AParExpr).n_expr
			nexpr.parent = null
			return nexpr
		end
		if eof.location > error.location then error = eof

		lexer = new InjectedLexer(source)
		lexer.injected_before.add new TKwdo
		lexer.injected_before.add new TEol
		lexer.injected_after.add new TEol
		lexer.injected_after.add new TKwend
		tree = (new Parser(lexer)).parse
		eof = tree.n_eof
		if not eof isa AError then
			var nblock = tree.n_base.n_classdefs.first.n_propdefs.first.as(AMethPropdef).n_block.as(ABlockExpr).n_expr.first.as(ADoExpr).n_block.as(ABlockExpr)
			nblock.n_kwend = null # drop injected token
			nblock.parent = null
			return nblock
		end
		if eof.location > error.location then error = eof

		lexer = new Lexer(source)
		tree = (new Parser(lexer)).parse
		eof = tree.n_eof
		if not eof isa AError then
			return tree.n_base.as(not null)
		end
		if eof.location > error.location then error = eof

		return error
	end