add `nerv.parse_args(argv, options)`

2 files changed, 119 insertions, 0 deletions

diff --git a/nerv/init.lua b/nerv/init.lua
index 4aa7a45..fdfd531 100644
--- a/nerv/init.lua
+++ b/nerv/init.lua
@@ -172,6 +172,109 @@ function nerv.include(filename)
     return dofile(nerv.dirname(caller) .. filename)
 end
 
+--- Parse the command-line options and arguments
+function nerv.parse_args(argv, options)
+    local is_opt_exp = "^[-](.*)$"
+    local sim_opt_exp = "^[-]([a-z]+)$"
+    local opt_exp = "^[-][-]([^=]+)$"
+    local opt_with_val_exp = "^[-][-]([^=]+)=([^=]+)$"
+    local opts = {}
+    local sopts = {}
+    local args = {}
+    local function err()
+        nerv.error("invalid format of option specification")
+    end
+    for _, v in ipairs(options) do
+        if type(v) ~= "table" or
+            (v[1] == nil and v[2] == nil) or
+            v[3] == nil then
+            err()
+        end
+        opt_full = v[1]
+        opt_short = v[2]
+        opt_type = v[3]
+        local opt_meta = {type = opt_type,
+                            desc = v.desc or "",
+                            val = v.default}
+        if opt_short ~= nil then
+            if type(opt_short) ~= "string" then err() end
+            if opt_type ~= "bool" then
+                nerv.error("only boolean option could have short form")
+            end
+            sopts[opt_short] = opt_meta
+        end
+        if opt_full ~= nil then
+            if type(opt_full) ~= "string" then err() end
+            opts[opt_full] = opt_meta
+        end
+    end
+    for _, token in ipairs(argv) do
+        if token:match(is_opt_exp) then
+            local k = token:match(sim_opt_exp)
+            if k then
+                for c in k:gmatch"." do
+                    if sopts[c] then
+                        sopts[c].val = true
+                    else
+                        nerv.error("invalid option -%s", c)
+                    end
+                end
+            else
+                local k = token:match(opt_exp)
+                if k then
+                    if opts[k] == nil then
+                        nerv.error("invalid option %s", token)
+                    end
+                    if opts[k].type ~= "bool" then
+                        nerv.error("invalid option --%s: " ..
+                                    "a %s value needs to be specified",
+                                    k, opts[k].type)
+                    else
+                        opts[k].val = true
+                    end
+                else
+                    local k, v = token:match(opt_with_val_exp)
+                    if k then
+                        if opts[k] == nil then
+                            nerv.error("invalid option %s", token)
+                        end
+                        if opts[k].type == "bool" then
+                            if v == "yes" then
+                                opts[k].val = true
+                            elseif v == "no" then
+                                opts[k].val = false
+                            else
+                                nerv.error("bool value should be \"yes\" or \"no\"")
+                            end
+                        elseif opts[k].type == "int" then
+                            local t = tonumber(v)
+                            opts[k].val = t
+                            if t == nil or math.floor(t) ~= t then
+                                nerv.error("int value is expected")
+                            end
+                        elseif opts[k].type == "float" then
+                            local t = tonumber(v)
+                            opts[k].val = t
+                            if t == nil then
+                                nerv.error("float value is expected")
+                            end
+                        elseif opts[k].type == "string" then
+                            opts[k].val = v
+                        else
+                            nerv.error("unrecognized type %s", opts[k].type)
+                        end
+                    else
+                        nerv.error("unrecognized option %s", token)
+                    end
+                end
+            end
+        else
+            table.insert(args, token)
+        end
+    end
+    return args, opts
+end
+
 -- the following lines trigger the initialization of basic modules
 
 nerv.include('matrix/init.lua')
diff --git a/nerv/test/parse_args.lua b/nerv/test/parse_args.lua
new file mode 100644
index 0000000..7146c3b
--- /dev/null
+++ b/nerv/test/parse_args.lua
@@ -0,0 +1,16 @@
+args, opts = nerv.parse_args(
+                    {"arg1", "arg2", "-abcd", "arg3",
+                    "--hehe", "--oh=no", "--uid=43",
+                    "highfive", "--str=hello"},
+
+                    {{"abandon", "a", "bool", default = false, desc = "abandon your belief"},
+                    {"bullshit", "b", "bool", default = false, desc = "start to bullshit"},
+                    {"cheat", "c", "bool", default = false, desc = "try to cheat"},
+                    {"delete", "d", "bool", default = false, desc = "remove everything"},
+                    {"hehe", "h", "bool", default = false, desc = "233333"},
+                    {"oh", "o", "bool", default = true, desc = "oh yes!"},
+                    {"uid", nil, "int", desc = "user uid"},
+                    {"str", nil, "string", desc = "test string"}}
+            )
+
+print(table.tostring(args), table.tostring(opts))