Introduce InvocationContext

For script caching we started storing script paths as absolute, but
displayed paths are generally relative to the starting directory. This
was hacked in as `script.base_directory`.

Introducing the `InvocationContext`.

To avoid global state, things that need information about how cyan
itself was invoked should take this as a parameter. Right now it only
contains the initial directory and project root directory.

Author: euclidianAce

build/cyan/cli.lua

@@ -35,6 +35,7 @@ build = {
       ["cyan.fs"] = "build/cyan/fs.lua",
       ["cyan.graph"] = "build/cyan/graph.lua",
       ["cyan.interaction"] = "build/cyan/interaction.lua",
+      ["cyan.invocation-context"] = "build/cyan/invocation-context.lua",
       ["cyan.log"] = "build/cyan/log.lua",
       ["cyan.meta"] = "build/cyan/meta.lua",
       ["cyan.sandbox"] = "build/cyan/sandbox.lua",
@@ -56,6 +57,7 @@ build = {
          ["cyan.fs"] = "src/cyan/fs.tl",
          ["cyan.graph"] = "src/cyan/graph.tl",
          ["cyan.interaction"] = "src/cyan/interaction.tl",
+         ["cyan.invocation-context"] = "src/cyan/invocation-context.tl",
          ["cyan.log"] = "src/cyan/log.tl",
          ["cyan.meta"] = "src/cyan/meta.tl",
          ["cyan.sandbox"] = "src/cyan/sandbox.tl",

build/cyan/command.lua

@@ -10,6 +10,8 @@ local common <const> = require("cyan.tlcommon")
 local config <const> = require("cyan.config")
 local decoration <const> = require("cyan.decoration")
 local fs <const> = require("cyan.fs")
+local invocation_context <const> = require("cyan.invocation-context")
+local lexical_path <const> = require("lexical-path")
 local log <const> = require("cyan.log")
 local script <const> = require("cyan.script")
 local util <const> = require("cyan.util")
@@ -107,15 +109,18 @@ command.new{
 }
 
 local starting_dir <const> = assert(fs.current_directory())
-script.base_directory = starting_dir
 local config_path <const> = config.find()
+local project_dir: lexical_path.Path
 if config_path then
    local config_dir <const> = config_path:copy()
    table.remove(config_dir)
    log.debug("Changing directory into: ", config_dir)
-   fs.change_directory(config_dir)
+   assert(fs.change_directory(config_dir))
+   project_dir = config_dir
 end
 
+local context <const> = invocation_context.new(starting_dir, project_dir)
+
 local loaded_config, config_errors <const>, config_warnings <const>
    = config.load()
 
@@ -181,7 +186,7 @@ do
 end
 
 local ok <const>, res <const> = xpcall(function()
-   exit = cmd.exec(args, loaded_config, starting_dir)
+   exit = cmd.exec(args, loaded_config, context)
 end, debug.traceback as function()) as (boolean, string)
 if not ok then
    log.err("Error executing command\n   ", res)