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3.11.2 Ternary Operator Definition

Ternary operators are introduced as extensions of binary operators. Their syntax is that of a double binary operator (OPERAND1 mark1 OPERAND2 mark2 OPERAND3) and their definition follows their appearance, with a binary operator definition grouping the first two operands and a second one adding the last operand.

Both binary operator definitions making up a ternary binary definition are of the struct x1f4_operator_type kind.

See struct x1f4_operator_type.

The second of them is linked into the first as an extension via a struct x1f4_2ndscope_type record pointed to by the extension2 field of the struct x1f4_operator_type definition.

See struct x1f4_2ndscope_type.

The extension2 field requires X1f4_E4_E2ND_LINK bit to be set by the flags attribute of the operator definition.

Where a binary operator appears matching the definition (name and list of arguments) of a ternary operator leading operator definition, the two operator definitions are to be combined.

Example: the binary real ‘%’ real operator and the ternary real ‘%’ real ‘^’ real operator would be introduced by a single struct x1f4_operator_type record matching the binary operator.

Where more ternary operators match in their leading operator definition (name and list of arguments), their definition are to be combined, with their trailing operator definitions following as a table.

Example: the ternary operators real ‘&’ real ‘*’ real and real ‘&’ real ‘*’ integer would be introduced by a single struct x1f4_operator_type record.

For ternary operators not sharing their leading binary operator definition, the trailing definition of the struct x1f4_operator_type kind is pointed by the rail attribute of the struct x1f4_2ndscope_type extension record of the leading operator definition. The bits field of the extension record sets the X1f4_E4_RAIL_MARK bit.

For ternary operators sharing their leading binary operator definition, the trailing definitions of the struct x1f4_operator_type kind are collected by a struct x1f4_raillist_type record, to be pointed by the rail attribute of the struct x1f4_2ndscope_type extension record of the leading operator definition. The bits field of the extension record sets the X1f4_E4_RAIL_LIST bit.

Where the leading binary operator definition does not function as a binary operator definition too (i.e. there’s no binary operator matching the lead of the ternary operator) the bits field of the struct x1f4_2ndscope_type extension record sets the X1f4_E4_RAIL_ONLY bit.

See struct x1f4_raillist_type.

See Operator Second Extension Scope Flags.

All ternary operators introduce a complementary function definition, to which the operators are expanded. The function definition is to match the operator definition in number of arguments (3), evaluation and arguments types. The function is introduced as a regular function extension to the trailing operator definition, with the X1f4_E4_CALL_LINK bit not being required.

See Expressive Operators.

The function pointer field in the struct x1f4_operator_type records introducing a ternary operator are not interpreted (except where the leading record is shared with a binary operator definition).

As ternary operators may share their leading operator definition record, they take most attributes from their second. Included are their precedence (from priority), associativity (from bits) and type (from type).

The type of the third operand is taken from the second int in the args array of the second operator definition. The first int is ignored.

Ternary operators may feature two marks between the second and the third operand, with one of them introduced by the first operator definition record as a suffix mark.

See Postfixed Binary Operators.

Ternary operators define two evaluation precedences, one to the left and one to the right. The first is taken from the leading operator definition record, the latter from the trailing operator definition record. The right precedence ought to be equal or lower than the left precedence (the right priority equal or greater than the left priority).

For ternary operators to evaluate right to left (like the ‘?’‘:’ and the ‘[’‘]’‘=’ operators do) the precedence in the leading operator definition should be higher than that in trailing operator definition.