From c1dcf01ad46651aed06fbf4d9da00f3370d7adac Mon Sep 17 00:00:00 2001
From: Gordon Hecker <gh@emlix.com>
Date: Tue, 22 Dec 2009 12:22:07 +0100
Subject: [PATCH] env: environment module

Signed-off-by: Gordon Hecker <gh@emlix.com>
---
 local/Makefile        |   1 +
 local/environment.lua | 106 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 local/environment.lua

diff --git a/local/Makefile b/local/Makefile
index 9070c9b..2a65f3e 100644
--- a/local/Makefile
+++ b/local/Makefile
@@ -110,6 +110,7 @@ clean:
 e2local.lc: $(TOPLEVEL)/generic/strict.lua \
 		result.lua \
 		loader.lua \
+		environment.lua \
 		$(TOPLEVEL)/generic/plugin.lua \
 		$(TOPLEVEL)/generic/scm.git.lua \
 		$(TOPLEVEL)/generic/transport.lua \
diff --git a/local/environment.lua b/local/environment.lua
new file mode 100644
index 0000000..5642b41
--- /dev/null
+++ b/local/environment.lua
@@ -0,0 +1,106 @@
+module("environment", package.seeall)
+require("sha1")
+
+function new()
+  local env = {}
+  local meta = { __index = environment }
+  setmetatable(env, meta)
+  env.dict = {}
+  env.sorted = {}
+  return env
+end
+
+function set(env, var, val)
+  env.dict[var] = val
+  table.insert(env.sorted, var)
+  table.sort(env.sorted)
+  return env
+end
+
+--- return a hash representing the environment
+function id(env)
+  local sha1 = sha1.sha1_init()
+  for var, val in env:iter() do
+    sha1:update(string.format("%s=%s", var, val))
+  end
+  return sha1:final()
+end
+
+--- merge environment from merge into env.
+-- override bool: shall vars from merge override vars from env?
+function merge(env, merge, override)
+  for i, var in ipairs(merge.sorted) do
+    if not env.dict[var] then
+      table.insert(env.sorted, var)
+    end
+    if not env.dict[var] or override then
+      env.dict[var] = merge.dict[var]
+    end
+  end
+  return env
+end
+
+--- iterate over the environment, in alphabetical order
+function iter(env)
+  local index = nil
+  local function _iter(t)
+    local var
+    index, var = next(t, index)
+    return var, env.dict[var]
+  end
+  return _iter, env.sorted
+end
+
+function unittest(env)
+  local function p(...)
+    --print(...)
+  end
+
+  e1 = new()
+  e1:set("var1.3", "val1.3")
+  e1:set("var1.1", "val1.1")
+  e1:set("var1.2", "val1.2")
+  e1:set("var1.4", "val1.4")
+  assert(e1:id() == "84C3CB1BFF877D12F500C05D7B133DA2B8BC0A4A")
+
+  e2 = new()
+  e2:set("var2.3", "val2.3")
+  e2:set("var2.1", "val2.1")
+  e2:set("var2.2", "val2.2")
+  e2:set("var2.4", "val2.4")
+  assert(e2:id() == "7E63398D2CA50AE2763042392628E8031AF30B02")
+
+  for var, val in e1:iter() do
+    p(var, val)
+  end
+
+  for var, val in e2:iter() do
+    p(var, val)
+  end
+
+  e1:merge(e2)
+  assert(e1:id() == "AF0572C5622CD21D3839AEA8D43234F6A67B7BA2")
+
+  for var, val in e1:iter() do
+    p(var, val)
+  end
+
+  -- check merge without / with override
+  e3 = new()
+  e3:set("var", "val3")
+  e4 = new()
+  e4:set("var", "val4")
+  e3:merge(e4, false)
+  for var, val in e3:iter() do
+    p(var, val)
+  end
+  assert(e3:id() == "0728A49396F211F911E69FB929F7FEE715F4F981")
+
+  e5 = new()
+  e5:set("var", "val5")
+  e5:merge(e4, true)
+  for var, val in e5:iter() do
+    p(var, val)
+  end
+  assert(e5:id() == "404AA226CF94A483FD61878682F8E2759998B197")
+end
-- 
2.39.5