+ LuaMacro

1 files changed, 70 insertions, 0 deletions

diff --git a/Tools/LuaMacro/macro/forall.lua b/Tools/LuaMacro/macro/forall.lua
new file mode 100644
index 0000000..8ec5c68
--- /dev/null
+++ b/Tools/LuaMacro/macro/forall.lua
@@ -0,0 +1,70 @@
+--------------------
+-- `forall` statement.
+-- The syntax is `forall VAR SELECT [if CONDN] do` where
+-- `SELECT` is either `in TBL` or `= START,FINISH`
+--
+-- For example,
+--
+--    forall name in {'one','two'} do print(name) end
+--
+--    forall obj in get_objects() if obj:alive() then
+--        obj:action()
+--    end
+--
+-- Using `forall`, we also define _list comprehensions_ like
+-- `L{s:upper() | s in names if s:match '%S+'}`
+--
+-- @module macro.forall
+
+local M = require 'macro'
+
+--- extended for statement.
+-- @macro forall
+M.define('forall',function(get,put)
+    local var = get:iden()
+    local t,v = get:next()
+    local rest,endt = get:list(M.upto_keywords('do','if'))
+    put:keyword 'for'
+    if v == 'in' then
+        put:iden '_' ',' :iden(var):keyword 'in'
+        put:iden 'ipairs' '(' :list(rest) ')'
+    elseif v == '=' then
+        put:iden(var) '=' :list(rest)
+    else
+        M.error("expecting in or =")
+    end
+    put:keyword 'do'
+    if endt[2] == 'if' then
+        rest,endt = get:list(M.upto_keywords('do'))
+        put:keyword 'if':list(rest):keyword 'then':iden '_END_END_'
+    end
+    return put
+end)
+
+--- list comprehension.
+-- Syntax is `L{expr | select}` where `select` is as in `forall`,
+-- or `L{expr for select}` where `select` is as in the regular `for` statement.
+-- @macro L
+-- @return a list of values
+-- @usage L{2*x | x in {1,2,3}} == {1,4,9}
+-- @usage L{2*x|x = 1,3} == {1,4,9}
+-- @usage L{{k,v} for k,v in pairs(t)}
+-- @see forall
+M.define('L',function(get,put)
+    local t,v = get:next() -- must be '{'
+    local expr,endt = get:list(function(t,v)
+        return t == '|' or t == 'keyword' and v == 'for'
+    end,'')
+    local select = get:list('}','')
+    put '(' : keyword 'function' '(' ')' :keyword 'local':iden 'res' '=' '{' '}'
+    if endt[2] == '|' then
+        put:iden'forall'
+    else
+        put:keyword 'for'
+    end
+    put:list(select):space():keyword'do'
+    put:iden'res' '[' '#' :iden'res' '+' :number(1) ']' '=' :list(expr):space()
+    put:keyword 'end' :keyword 'return' : iden 'res' :keyword 'end' ')' '(' ')'
+    put:iden '_POP_':string'L'
+    return put
+end)