[examples/ls] Add ls example.

examples/ls.lua

@@ -0,0 +1,140 @@
+#!/bin/env lua
+-- Basic Unix-style directory listing.
+-- Demonstrates low-level raw use of a Dir, in order to list even . and .. to
+-- output.
+--
+-- NOTE: the simplistic argument parser doesn't handle merged options like -ht. 
+--
+-- Example uses:
+-- lua ls.lua
+-- lua ls.lua -a ..
+-- lua ls.lua -a -h src
+-- lua ls.lua -a -t a.dir b.dir c.dir
+--
+-- Author: Lorenzo Cogotti, The DoubleFourteen Code Forge
+
+local osx = require 'osx'
+local io = require 'io'
+local write = io.write
+
+local sep = osx.sep
+local aflag = false  -- list hidden
+local tflag = false  -- sort by time
+local Sflag = false  -- sort by size
+local hflag = false  -- print size, human readable (equivalent to -sh)
+
+local function parseargs(...)
+    local args = {}
+
+    for i = 1,select('#', ...) do
+        local arg = select(i, ...)
+
+        if arg == '-a' then
+            aflag = true
+        elseif arg == '-t' then
+            tflag, Sflag = true, false
+        elseif arg == '-S' then
+            Sflag, tflag = true, false
+        elseif arg == '-h' then
+            hflag = true
+        else
+            args[#args+1] = arg
+        end
+    end
+    if #args == 0 then
+        args = { "." } -- current directory by default
+    end
+    return args
+end
+
+local function ksize(sz)
+    sz = sz / 1024
+
+    if sz > 0 then
+        return ("%.1fK"):format(sz)
+    else
+        return "0"
+    end
+end
+
+local function listfilenames(filenames, bufs, total)
+    table.sort(filenames) -- always sort by name
+
+    if Sflag then
+        table.sort(filenames, function (a, b)
+            a, b = bufs[a], bufs[b]
+
+            local asize = a.size or -1
+            local bsize = b.size or -1
+            return asize > bsize -- sort by size, largest first
+        end)
+    elseif tflag then
+        table.sort(filenames, function(a, b)
+            a, b = bufs[a], bufs[b]
+
+            local atime = a.mtime or -1
+            local btime = b.mtime or -1
+            return atime > btime  -- sort by time, latest first
+        end)
+    end
+
+    if hflag then
+        write(ksize(total), " total\n")
+    end
+    for _, filename in ipairs(filenames) do
+        local buf = bufs[filename]
+
+        if hflag then
+            write(ksize(buf.size or 0), " ")
+        end
+        write(filename, '\n')
+    end
+end
+
+local function ls(path)
+    local dir, err = osx.opendir(path)
+    if not dir then
+        io.stderr:write(err, "\n")
+        return
+    end
+
+    local filenames = {}
+    local bufs = {}
+    local total = 0
+
+    while true do
+    :: nextfilename ::
+        local filename, err = dir:readdir()
+        if err then
+            -- Report, but tolerate error
+            io.stderr:write(path, ": ", err, "\n")
+        end
+        if not filename then
+            break  -- done with this dir
+        end
+        if filename:sub(1, 1) == '.' and not aflag then
+            goto nextfilename  -- skip hidden
+        end
+
+        -- stat() file, update counters and store for listing
+        local filepath = path..sep..filename
+        local buf, err = osx.stat(filepath)
+        if not buf then
+            io.stderr:write(filepath, ": ", err, "\n")
+            goto nextfilename
+        end
+
+        total = total + (buf.size or 0)
+        filenames[#filenames+1] = filename
+        bufs[filename] = buf
+    end
+
+    -- Print file list
+    listfilenames(filenames, bufs, total)
+    dir:close()  -- NOTE: could have marked this with <close>
+end
+
+local args = parseargs(...)
+for _,path in ipairs(args) do
+    ls(path)
+end