Roland Ver. 4.5 Información técnica descargar pdf (Pagina 137)

Chapter 10: Using Implicit Rules 127

10.8 Implicit Rule Search Algorithm

Here is the procedure make uses for searching for an implicit rule for a target t. This

procedure is followed for each double-colon rule with no recipe, for each target of ordinary

rules none of which have a recipe, and for each prerequisite that is not the target of any

rule. It is also followed recursively for prerequisites that come from implicit rules, in the

search for a chain of rules.

Suﬃx rules are not mentioned in this algorithm because suﬃx rules are converted to

equivalent pattern rules once the makeﬁles have been read in.

For an archive member target of the form ‘archive(member)’, the following algorithm

is run twice, ﬁrst using the entire target name t, and second using ‘(member)’ as the target

t if the ﬁrst run found no rule.

1. Split t into a directory part, called d, and the rest, called n. For example, if t is

‘src/foo.o’, then d is ‘src/’ and n is ‘foo.o’.

2. Make a list of all the pattern rules one of whose targets matches t or n. If the target

pattern contains a slash, it is matched against t; otherwise, against n.

3. If any rule in that list is not a match-anything rule, then remove all non-terminal

match-anything rules from the list.

4. Remove from the list all rules with no recipe.

5. For each pattern rule in the list:

a. Find the stem s, which is the nonempty part of t or n matched by the ‘%’ in the

target pattern.

b. Compute the prerequisite names by substituting s for ‘%’; if the target pattern

does not contain a slash, append d to the front of each prerequisite name.

c. Test whether all the prerequisites exist or ought to exist. (If a ﬁle name is men-

tioned in the makeﬁle as a target or as an explicit prerequisite, then we say it

ought to exist.)

If all prerequisites exist or ought to exist, or there are no prerequisites, then this

rule applies.

6. If no pattern rule has been found so far, try harder. For each pattern rule in the list:

a. If the rule is terminal, ignore it and go on to the next rule.

b. Compute the prerequisite names as before.

c. Test whether all the prerequisites exist or ought to exist.

d. For each prerequisite that does not exist, follow this algorithm recursively to see

if the prerequisite can be made by an implicit rule.

e. If all prerequisites exist, ought to exist, or can be made by implicit rules, then this

rule applies.

7. If no implicit rule applies, the rule for .DEFAULT, if any, applies. In that case, give t

the same recipe that .DEFAULT has. Otherwise, there is no recipe for t.

Once a rule that applies has been found, for each target pattern of the rule other than

the one that matched t or n, the ‘%’ in the pattern is replaced with s and the resultant

ﬁle name is stored until the recipe to remake the target ﬁle t is executed. After the recipe

1 2 ... 132 133 134 135 136 137 138 139 140 141 142 ... 211 212

Sin comentarios

Roland Ver. 4.5 Información técnica Pagina 137