Add dependency caching and helper functions

Dependencies/libpqxx/Libpqxx.lua

@@ -68,8 +68,12 @@ Solution.Util.CreateStaticLib(dep.Name, Solution.Projects.Current.BinDir, dep.De
 end)
 
 Solution.Util.CreateDep(dep.NameLow, dep.Dependencies, function()
-    local baseDir = dep.Path .. "/Libpqxx"
-    local _, _, foundLibs = getPostgresInfo()
-    Solution.Util.SetIncludes({baseDir .. "/include"})
+    local foundLibs = Solution.Util.GetDepCache(dep.NameLow, "cache")
+    if not foundLibs then
+        local _, _, foundLibs = getPostgresInfo()
+        Solution.Util.SetDepCache(dep.NameLow, "cache", foundLibs)
+    end
+
+    Solution.Util.SetIncludes({dep.Path .. "/Libpqxx/include"})
     Solution.Util.SetLinks({ dep.Name, foundLibs })
 end)

Premake/ProjectUtil.lua

@@ -97,6 +97,32 @@ Solution.Util.CreateDepTable = function(name, dependencies)
     return dependency
 end
 
+Solution.Util.GetDepTable = function(depName)
+    local depInternalName = "Dependency-" .. depName
+    local dep = _G[depInternalName]
+    if (dep == nil) then
+        Solution.Util.PrintError("Tried to fetch undeclared dependency '" .. depName .. "'")
+    end
+
+    return dep
+end
+
+-- Cache a value inside the dep table
+Solution.Util.SetDepCache = function(depName, key, data)
+    local dep = Solution.Util.GetDepTable(depName)
+    dep.Cache[key] = data
+end
+
+-- Retrieve a cached value from the dep table, or return nil if not cached
+Solution.Util.GetDepCache = function(depName, key)
+    local dep = Solution.Util.GetDepTable(depName)
+    if dep.Cache[key] then
+        return dep.Cache[key]
+    end
+
+    return nil
+end
+
 Solution.Util.IncludeSubmodule = function(name, rootDir, binDir)
     local submoduleRootDir = path.getabsolute("Submodules/".. name .. "/", rootDir)
     local submoduleBuildDir = path.getabsolute("Build/".. name .. "/", rootDir)
@@ -295,7 +321,8 @@ Solution.Util.CreateDep = function(name, dependencies, callback)
     local dependencyTable = 
     {
         Callback = callback,
-        Dependencies = dependencies
+        Dependencies = dependencies,
+        Cache = {}
     }
 
     _G[internalName] = dependencyTable
@@ -406,6 +433,12 @@ Solution.Util.ClearFilter = function()
     filter { }
 end
 
+Solution.Util.MergeIntoTable = function(t, x)
+    for _, v in pairs(x) do
+        table.insert(t, v)
+    end
+end
+
 if InitBuildSettings == nil then
     function InitBuildSettings(silentFailOnDuplicateSetting)
         if BuildSettings == nil then