To manage the set of named paragraph macros in a section.

§1. We store these like so:

typedef struct para_macro {
    struct text_stream *macro_name;  usually long, like "Create a paragraph macro here"
    struct paragraph *defining_paragraph;  as printed in small type after the name in any usage
    struct source_line *defn_start;  it ends at the end of its defining paragraph
    struct linked_list *macro_usages;  of macro_usage: only computed for weaves
} para_macro;

§2. Each section has its own linked list of paragraph macros, since the scope for the usage of these is always a single section.

para_macro *Macros::create(section *S, paragraph *P, source_line *L, text_stream *name) {
    para_macro *pmac = CREATE(para_macro);
    pmac->macro_name = Str::duplicate(name);
    pmac->defining_paragraph = P;
    P->defines_macro = pmac;
    pmac->defn_start = L->next_line;
    pmac->macro_usages = NEW_LINKED_LIST(macro_usage);
    ADD_TO_LINKED_LIST(pmac, para_macro, S->macros);
    return pmac;

§3. Paragraph macro search. The scope for looking up paragraph macro names is a single section, not the entire web. So you can't expand a macro from another section, but then again, you can use the same macro name twice in different sections; and lookup is much faster.

para_macro *Macros::find_by_name(text_stream *name, section *scope) {
    para_macro *pmac;
    LOOP_OVER_LINKED_LIST(pmac, para_macro, scope->macros)
        if (Str::eq(name, pmac->macro_name))
            return pmac;
    return NULL;