Merge pull request bakaq#11 from constraintAutomaton/feature/hash-dependencies

Add the ability to use git dependencies with a fix hash

Author: bakaq

README.md

@@ -27,7 +27,7 @@ dependencies([
 ```
 
 Copy the `pkg.pl` file into your project. It is both the dependency manager and
-the package loader. Use `scryer-prolog pkg.pl -g pkg_install,halt` to download
+the package loader. Use `scryer-prolog pkg.pl -g pkg_install,halt.` to download
 the dependencies to a `scryer_libs` directory (it doesn't handle transitive
 dependencies yet). You can then import packages in your code as follows:
 

example/main.pl

@@ -6,6 +6,7 @@
 :- use_module(pkg(testing)).
 :- use_module(pkg(foo_branch)).
 :- use_module(pkg(foo_tag)).
+:- use_module(pkg(foo)).
 
 % You can then use the predicates exported by the main file of the dependency
 % in the rest of the program.
@@ -17,3 +18,5 @@
 
 test("test if the branch dependency works", (tag(exist))).
 test("test if the tag dependency works", (branch(exist))).
+test("test if the hash dependency works", (hash(exist))).
+

example/scryer-manifest.pl

@@ -8,5 +8,7 @@
     % A git url to clone at a specific branch
     git("https://github.com/constraintAutomaton/test-prolog-package-manager.git", branch("branch")),
     % A git url to clone at a tag
-    git("https://github.com/constraintAutomaton/test-prolog-package-manager.git", tag("tag"))
+    git("https://github.com/constraintAutomaton/test-prolog-package-manager.git", tag("tag")),
+    % A git url to clone at a specific commit hash
+    git("https://github.com/constraintAutomaton/test-prolog-package-manager.git", hash("d19fefc1d7907f6675e181601bb9b8b94561b441"))
 ]).

pkg.pl

@@ -90,3 +90,9 @@
 
 git_command(git(Url, tag(Tag)), Command) :-
     git_command(git(Url, branch(Tag)), Command).
+
+git_command(git(Url, hash(Hash)), Command) :-
+    CloneCommand = ["git clone --quiet --depth 1 --single-branch ", Url, " scryer_libs/tmp "],
+    GetHashCommitCommand = [" && cd scryer_libs/tmp  >/dev/null && git fetch --quiet --depth 1 origin ", Hash, " && git checkout --quiet ", Hash, " && cd ../  >/dev/null"],
+    append(CloneCommand, GetHashCommitCommand,  Segments), 
+    append(Segments, Command).