show: accept a substring when unambiguous and matches a single entry

4 files changed, 37 insertions, 3 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 960ac47d..61c46ff2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+## What's new
+
+### Features
+
+* The `show` command can now accept a substring of the rock's name,
+  like `list`.
+
 ## What's new in LuaRocks 3.3.1
 
 This is a bugfix release:
diff --git a/spec/show_spec.lua b/spec/show_spec.lua
index a0987de0..c2840d29 100644
--- a/spec/show_spec.lua
+++ b/spec/show_spec.lua
@@ -78,6 +78,17 @@ describe("LuaRocks show #integration", function()
       run.luarocks_bool("show luacov 0.13.0")
    end)
 
+   it("can find by substring", function()
+      assert(run.luarocks_bool("install has_build_dep --server=" .. testing_paths.fixtures_dir .. "/a_repo" ))
+      assert.match("a_build_dep", run.luarocks("show has_"))
+   end)
+
+   it("fails when substring matches multiple", function()
+      assert(run.luarocks_bool("install has_build_dep --server=" .. testing_paths.fixtures_dir .. "/a_repo" ))
+      assert(run.luarocks_bool("install a_build_dep --server=" .. testing_paths.fixtures_dir .. "/a_repo" ))
+      assert.match("multiple installed packages match the name 'dep'", run.luarocks("show dep"))
+   end)
+
    it("shows #build_dependencies", function()
       assert(run.luarocks_bool("install has_build_dep --server=" .. testing_paths.fixtures_dir .. "/a_repo" ))
       assert.match("a_build_dep", run.luarocks("show has_build_dep"))
diff --git a/src/luarocks/cmd/show.lua b/src/luarocks/cmd/show.lua
index 8bb61b94..6d8047d5 100644
--- a/src/luarocks/cmd/show.lua
+++ b/src/luarocks/cmd/show.lua
@@ -261,7 +261,7 @@ end
 --- Driver function for "show" command.
 -- @return boolean: True if succeeded, nil on errors.
 function show.command(args)
-   local query = queries.new(args.rock, args.namespace, args.version)
+   local query = queries.new(args.rock, args.namespace, args.version, true)
    
    local name, version, repo, repo_url = search.pick_installed_rock(query, args.tree)
    if not name then
diff --git a/src/luarocks/search.lua b/src/luarocks/search.lua
index 80e4caaa..99a969c1 100644
--- a/src/luarocks/search.lua
+++ b/src/luarocks/search.lua
@@ -361,9 +361,25 @@ function search.pick_installed_rock(query, given_tree)
       return nil, "cannot find package "..tostring(query).."\nUse 'list' to find installed rocks."
    end
 
+   if not result_tree[query.name] and next(result_tree, next(result_tree)) then
+      local out = { "multiple installed packages match the name '"..tostring(query).."':\n\n" }
+      for name, _ in util.sortedpairs(result_tree) do
+         table.insert(out, "   " .. name .. "\n")
+      end
+      table.insert(out, "\nPlease specify a single rock.\n")
+      return nil, table.concat(out)
+   end
+
    local version = nil
    local repo_url
-   local _, versions = util.sortedpairs(result_tree)()
+
+   local name, versions
+   if result_tree[query.name] then
+      name, versions = query.name, result_tree[query.name]
+   else
+      name, versions = util.sortedpairs(result_tree)()
+   end
+
    --question: what do we do about multiple versions? This should
    --give us the latest version on the last repo (which is usually the global one)
    for vs, repositories in util.sortedpairs(versions, vers.compare_versions) do
@@ -372,7 +388,7 @@ function search.pick_installed_rock(query, given_tree)
    end
 
    local repo = tree_map[repo_url]
-   return query.name, version, repo, repo_url
+   return name, version, repo, repo_url
 end
 
 return search