6. Statement tokens

The syntax for introducing a statement token is simply:

#pragma token STATEMENT init_globs#
int g(int);
int f(int x) {
	init_globs return g(x);
}

Internal statement token identifiers reside in the macro name space. The optional name space, TAG, should not appear in statement token introductions.

The use of statement tokens is analogous to the use of expression tokens (see §5). A new symbol, stat-token-name, has been introduced into the syntax analysis at phase 7 of translation as defined in the ISO C standard. This token is passed through to the syntax analyser whenever the preprocessor encounters an identifier referring to a statement token. A stat-token-name can only occur as part of the statement syntax (ISO C standard, section 6.6).

As with expression tokens, statement tokens are defined using #define statements. An example of this is shown below:

#pragma token STATEMENT i_globs#
#define i_globs {
	int i = x;
	x = 3;
}

The constraints on the definition of statement tokens are:

• the use of labels is forbidden unless the definition of the statement token occurs at the outer level (i.e outside of any compound statement forming a function definition);

• the use of return within the defining statement is not allowed.

The semantics of the defining statement are precisely the same as the semantics of a compound statement forming the definition of a function with no parameters and void result. The definition of statement tokens carries the same implications for phases of translation as the definition of expression tokens (see F.5 Expression tokens).