+ Penlight

1 files changed, 171 insertions, 0 deletions

diff --git a/Data/Libraries/Penlight/lua/pl/input.lua b/Data/Libraries/Penlight/lua/pl/input.lua
new file mode 100644
index 0000000..f81de87
--- /dev/null
+++ b/Data/Libraries/Penlight/lua/pl/input.lua
@@ -0,0 +1,171 @@
+--- Iterators for extracting words or numbers from an input source.
+--
+--    require 'pl'
+--    local total,n = seq.sum(input.numbers())
+--    print('average',total/n)
+--
+-- _source_ is defined as a string or a file-like object (i.e. has a read() method which returns the next line)
+--
+-- See @{06-data.md.Reading_Unstructured_Text_Data|here}
+--
+-- Dependencies: `pl.utils`
+-- @module pl.input
+local strfind = string.find
+local strsub = string.sub
+local strmatch = string.match
+local utils = require 'pl.utils'
+local unpack = utils.unpack
+local pairs,type,tonumber = pairs,type,tonumber
+local patterns = utils.patterns
+local io = io
+
+local input = {}
+
+--- create an iterator over all tokens.
+-- based on allwords from PiL, 7.1
+-- @func getter any function that returns a line of text
+-- @string pattern
+-- @string[opt] fn  Optionally can pass a function to process each token as it's found.
+-- @return an iterator
+function input.alltokens (getter,pattern,fn)
+    local line = getter()  -- current line
+    local pos = 1           -- current position in the line
+    return function ()      -- iterator function
+        while line do         -- repeat while there are lines
+          local s, e = strfind(line, pattern, pos)
+          if s then           -- found a word?
+            pos = e + 1       -- next position is after this token
+            local res = strsub(line, s, e)     -- return the token
+            if fn then res = fn(res) end
+            return res
+          else
+            line = getter()  -- token not found; try next line
+            pos = 1           -- restart from first position
+          end
+        end
+        return nil            -- no more lines: end of traversal
+   end
+end
+local alltokens = input.alltokens
+
+-- question: shd this _split_ a string containing line feeds?
+
+--- create a function which grabs the next value from a source. If the source is a string, then the getter
+-- will return the string and thereafter return nil. If not specified then the source is assumed to be stdin.
+-- @param f a string or a file-like object (i.e. has a read() method which returns the next line)
+-- @return a getter function
+function input.create_getter(f)
+    if f then
+        if type(f) == 'string' then
+            local ls = utils.split(f,'\n')
+            local i,n = 0,#ls
+            return function()
+                i = i + 1
+                if i > n then return nil end
+                return ls[i]
+            end
+        else
+            -- anything that supports the read() method!
+            if not f.read then error('not a file-like object') end
+            return function() return f:read() end
+        end
+    else
+        return io.read  -- i.e. just read from stdin
+    end
+end
+
+--- generate a sequence of numbers from a source.
+-- @param f A source
+-- @return An iterator
+function input.numbers(f)
+    return alltokens(input.create_getter(f),
+        '('..patterns.FLOAT..')',tonumber)
+end
+
+--- generate a sequence of words from a source.
+-- @param f A source
+-- @return An iterator
+function input.words(f)
+    return alltokens(input.create_getter(f),"%w+")
+end
+
+local function apply_tonumber (no_fail,...)
+    local args = {...}
+    for i = 1,#args do
+        local n = tonumber(args[i])
+        if  n == nil then
+            if not no_fail then return nil,args[i] end
+        else
+            args[i] = n
+        end
+    end
+    return args
+end
+
+--- parse an input source into fields.
+-- By default, will fail if it cannot convert a field to a number.
+-- @param ids a list of field indices, or a maximum field index
+-- @string delim delimiter to parse fields (default space)
+-- @param f a source @see create_getter
+-- @tab opts option table, `{no_fail=true}`
+-- @return an iterator with the field values
+-- @usage for x,y in fields {2,3} do print(x,y) end -- 2nd and 3rd fields from stdin
+function input.fields (ids,delim,f,opts)
+  local sep
+  local s
+  local getter = input.create_getter(f)
+  local no_fail = opts and opts.no_fail
+  local no_convert = opts and opts.no_convert
+  if not delim or delim == ' ' then
+      delim = '%s'
+      sep = '%s+'
+      s = '%s*'
+  else
+      sep = delim
+      s = ''
+  end
+  local max_id = 0
+  if type(ids) == 'table' then
+    for i,id in pairs(ids) do
+      if id > max_id then max_id = id end
+    end
+  else
+    max_id = ids
+    ids = {}
+    for i = 1,max_id do ids[#ids+1] = i end
+  end
+  local pat = '[^'..delim..']*'
+  local k = 1
+  for i = 1,max_id do
+    if ids[k] == i then
+      k = k + 1
+      s = s..'('..pat..')'
+    else
+      s = s..pat
+    end
+    if i < max_id then
+      s = s..sep
+    end
+  end
+  local linecount = 1
+  return function()
+    local line,results,err
+    repeat
+        line = getter()
+        linecount = linecount + 1
+        if not line then return nil end
+        if no_convert then
+            results = {strmatch(line,s)}
+        else
+            results,err = apply_tonumber(no_fail,strmatch(line,s))
+            if not results then
+                utils.quit("line "..(linecount-1)..": cannot convert '"..err.."' to number")
+            end
+        end
+    until #results > 0
+    return unpack(results)
+  end
+end
+
+return input
+