gsl-shell.git - gsl-shell

diff --git a/expr-actions.lua b/expr-actions.lua
new file mode 100644
index 00000000..3e82cf1c
--- /dev/null
+++ b/expr-actions.lua

@@ -0,0 +1,64 @@

+

+local type = type

+

+local function mult(a, b)

+ if a == 1 then return b end

+ if b == 1 then return a end

+ return {operator= '*', a, b}

+end

+

+local function infix_action(sym, a, b)

+ if sym == '*' then

+ return mult(a, b)

+ else

+ return {operator= sym, a, b}

+ end

+end

+

+local function prefix_action(sym, a)

+ return {operator= sym, a}

+end

+

+local function enum_action(id)

+ return "%" .. id

+end

+

+local function func_eval_action(func_name, arg_expr)

+ return {func = func_name, arg = arg_expr}

+end

+

+local function ident_action(id) return id end

+

+local function literal_action(name)

+ return {literal= name}

+end

+

+-- return true iff expr is a variable (with enums or not).

+-- if it is a variable returns, in addition, the var_name and the enumeration flag

+local function is_variable(expr)

+ if type(expr) == 'string' then

+ local esc_name = string.match(expr, "^%%(.*)")

+ return true, esc_name or expr, (esc_name ~= nil)

+ else

+ return false

+ end

+end

+

+local function is_number(expr)

+ return type(expr) == 'number'

+end

+

+return {

+ infix = infix_action,

+ ident = ident_action,

+ literal = literal_action,

+ prefix = prefix_action,

+ enum = enum_action,

+ func_eval = func_eval_action,

+ number = function(x) return x end,

+ exprlist = function(a, ls) if ls then ls[#ls+1] = a else ls = {a} end; return ls end,

+ schema = function(x, y, conds, enums) return {x= x, y= y, conds= conds, enums= enums} end,

+

+ is_variable = is_variable,

+ is_number = is_number,

+}