iter: take advantage of @let if available.

- All iterator definitions must provide a __temp_xxx macro
  now to declare temporary variables, even if empty.

- Fixing str to use a temporary variable for the string length,
  and string object, so it's not evaluated multiple times.

- Fixing argmax and argmin to use temporary variables whose names
  are derived from the argument symbols, so that clashes between
  multiple occurrences of these in one loop are prevented.

1 files changed, 54 insertions, 15 deletions

diff --git a/cppawk-include/iter.h b/cppawk-include/iter.h
index 7246f2c..8703fb1 100644
--- a/cppawk-include/iter.h
+++ b/cppawk-include/iter.h
@@ -48,12 +48,20 @@
 #define dostring(index, chr, str) __dostring(index, chr, str)
 #define dofields(index, val) __dofields(index, val)
 
-#define loop(...) for (__loop_init(__VA_ARGS__);                              \
+#define loop(...) __loop_temp(__VA_ARGS__)                                    \
+                  for (__loop_init(__VA_ARGS__);                              \
                        (__loop_test(__VA_ARGS__) ||                           \
                         __loop_fini(__VA_ARGS__)) &&                          \
                        __loop_prep(__VA_ARGS__);                              \
                        __loop_step(__VA_ARGS__))
 
+#if __have_let
+#define __loop_temp(...) __let(__varexpand(__temp_first, __temp_next,         \
+                                           __VA_ARGS__))
+#else
+#define __loop_temp(...)
+#endif
+
 #define __loop_init(...) __prog(__varexpand(__init_first, __init_next,        \
                                           __VA_ARGS__))
 #define __loop_test(...) __nd(__varexpand(__test_first, __test_next,          \
@@ -78,6 +86,9 @@
                                  __step_ ## args)
 #define __cross_next(prev, args) prev __cross_first(args)
 
+#define __temp_first(args) __temp_ ## args
+#define __temp_next(prev, args) prev __temp_ ## args
+
 #define __init_first(args) __init_ ## args
 #define __init_next(prev, args) prev, __init_ ## args
 
@@ -93,36 +104,44 @@
 #define __step_first(args) __step_ ## args
 #define __step_next(prev, args) prev, __step_ ## args
 
-#define __init_str(idx, ch, str) idx = 1
-#define __test_str(idx, ch, str) idx <= length(str)
-#define __prep_str(idx, ch, str) ch = substr(str, idx, 1)
+#define __str_s __g(ch)
+#define __str_len __g(idx)
+#define __temp_str(idx, ch, str) __str_s, __str_len,
+#define __init_str(idx, ch, str) __str_s = (str), __str_len = length(__str_s), idx = 1
+#define __test_str(idx, ch, str) idx <= __str_len
+#define __prep_str(idx, ch, str) ch = substr(__str_s, idx, 1)
 #define __fini_str(idx, ch, str) 1
 #define __step_str(idx, ch, str) idx++
 
+#define __temp_range(idx, from, to)
 #define __init_range(idx, from, to) idx = (from)
 #define __test_range(idx, from, to) idx <= (to)
 #define __prep_range(idx, from, to) 1
 #define __fini_range(idx, from, to) 1
 #define __step_range(idx, from, to) idx++
 
+#define __temp_range_step(idx, from, to, step)
 #define __init_range_step(idx, from, to, step) idx = (from)
 #define __test_range_step(idx, from, to, step) idx <= (to)
 #define __prep_range_step(idx, from, to, step) 1
 #define __fini_range_step(idx, from, to, step) 1
 #define __step_range_step(idx, from, to, step) idx += (step)
 
+#define __temp_from(idx, from)
 #define __init_from(idx, from) idx = (from)
 #define __test_from(idx, from) 1
 #define __prep_from(idx, from) 1
 #define __fini_from(idx, from) 1
 #define __step_from(idx, from) idx++
 
+#define __temp_from_step(idx, from, step)
 #define __init_from_step(idx, from, step) idx = (from)
 #define __test_from_step(idx, from, step) 1
 #define __prep_from_step(idx, from, step) 1
 #define __fini_from_step(idx, from, step) 1
 #define __step_from_step(idx, from, step) idx += (step)
 
+#define __temp_first_then(var, first, then)
 #define __init_first_then(var, first, then) (var = (first))
 #define __test_first_then(var, first, then) 1
 #define __prep_first_then(var, first, then) 1
@@ -131,46 +150,54 @@
 
 #define for_var(var, expr) first_then(var, expr, expr)
 
+#define __temp_list(iter, var, list)
 #define __init_list(iter, var, list) iter = (list)
 #define __test_list(iter, var, list) !__endp(iter)
 #define __prep_list(iter, var, list) var = __car(iter)
 #define __fini_list(iter, var, list) 0
 #define __step_list(iter, var, list) iter = __cdr(iter)
+#define __temp___list(iter, var, list)
 #define __init___list(iter, var, list) iter = (list)
 #define __test___list(iter, var, list) !__endp(iter)
 #define __prep___list(iter, var, list) var = __car(iter)
 #define __fini___list(iter, var, list) 0
 #define __step___list(iter, var, list) iter = __cdr(iter)
 
+#define __temp_fields(var) __g(var),
 #define __init_fields(var) __g(var) = 1
 #define __test_fields(var) __g(var) <= NF
 #define __prep_fields(var) var = $ __g(var)
 #define __fini_fields(var) 1
 #define __step_fields(var) __g(var)++
 
+#define __temp_keys(key, array) __g(key),
 #define __init_keys(key, array) __g(key) = __keys(array)
 #define __test_keys(key, array) !__endp(__g(key))
 #define __prep_keys(key, array) key = __car(__g(key))
 #define __fini_keys(key, array) 1
 #define __step_keys(key, array) __g(key) = __cdr(__g(key))
+#define __temp___keys(key, array) __g(key),
 #define __init___keys(key, array) __g(key) = __keys(array)
 #define __test___keys(key, array) !__endp(__g(key))
 #define __prep___keys(key, array) key = __car(__g(key))
 #define __fini___keys(key, array) 1
 #define __step___keys(key, array) __g(key) = __cdr(__g(key))
 
+#define __temp_collect(var, expr)
 #define __init_collect(var, expr) var = __list_begin()
 #define __test_collect(var, expr) 1
 #define __prep_collect(var, expr) var = __list_add(var, expr)
 #define __fini_collect(var, expr) var = __list_end(var)
 #define __step_collect(var, expr) 1
 
+#define __temp_collect_plus(var, expr)
 #define __init_collect_plus(var, expr) var = __list_begin()
 #define __test_collect_plus(var, expr) 1
 #define __prep_collect_plus(var, expr) var = __list_add(var, expr)
 #define __fini_collect_plus(var, expr) var = __list_end(__list_add(var, expr))
 #define __step_collect_plus(var, expr) 1
 
+#define __temp_summing(var, expr)
 #define __init_summing(var, expr) var = 0
 #define __test_summing(var, expr) 1
 #define __prep_summing(var, expr) var += (expr)
@@ -182,6 +209,7 @@ function __loop_max(a, b)
   return a > b ? a : b
 }
 
+#define __temp_maximizing(var, expr)
 #define __init_maximizing(var, expr) var = nil
 #define __test_maximizing(var, expr) 1
 #define __prep_maximizing(var, expr) var = (__null(var)                       \
@@ -195,6 +223,7 @@ function __loop_min(a, b)
   return a > b ? b : a
 }
 
+#define __temp_minimizing(var, expr)
 #define __init_minimizing(var, expr) var = nil
 #define __test_minimizing(var, expr) 1
 #define __prep_minimizing(var, expr) var = (__null(var)                       \
@@ -208,15 +237,20 @@ function __loop_argmax(a, arga, b, argb)
   return a > b ? arga : argb;
 }
 
-#define __init_argmax(amx, arg, expr) (__g(mx) = 0) || (amx = 0)
+#define __am_max __g(amx)
+#define __am_min __g(ami)
+#define __am_old __g(arg)
+
+#define __temp_argmax(amx, arg, expr) __am_max, __am_old,
+#define __init_argmax(amx, arg, expr) (__am_max = 0) || (amx = 0)
 #define __test_argmax(amx, arg, expr) 1
-#define __prep_argmax(amx, arg, expr) ((__g(om) = __g(mx)) || 1) &&           \
-                                      ((__g(mx) =                             \
-                                        (__null(__g(mx))                      \
+#define __prep_argmax(amx, arg, expr) ((__am_old = __am_max) || 1) &&         \
+                                      ((__am_max =                            \
+                                        (__null(__am_max)                     \
                                          ? expr                               \
-                                         : __loop_max(__g(mx),                \
+                                         : __loop_max(__am_max,               \
                                                       expr))) || 1) &&        \
-                                      ((__g(om) != __g(mx)) ? amx = arg : 1)
+                                      ((__am_old != __am_max) ? amx = arg : 1)
 #define __fini_argmax(amx, arg, expr) 1
 #define __step_argmax(amx, arg, expr) 1
 
@@ -225,30 +259,34 @@ function __loop_argmin(a, arga, b, argb)
   return a < b ? arga : argb;
 }
 
+#define __temp_argmin(ami, arg, expr) __am_min, __am_old,
 #define __init_argmin(ami, arg, expr) (__g(mi) = 0) || (ami = 0)
 #define __test_argmin(ami, arg, expr) 1
-#define __prep_argmin(ami, arg, expr) ((__g(om) = __g(mi)) || 1) &&           \
-                                      ((__g(mi) =                             \
-                                        (__null(__g(mi))                      \
+#define __prep_argmin(ami, arg, expr) ((__am_old = __am_min) || 1) &&         \
+                                      ((__am_min =                            \
+                                        (__null(__am_min)                     \
                                          ? expr                               \
-                                         : __loop_min(__g(mi),                \
+                                         : __loop_min(__am_min,               \
                                                       expr))) || 1) &&        \
-                                      ((__g(om) != __g(mi)) ? ami = arg : 1)
+                                      ((__am_old != __am_min) ? ami = arg : 1)
 #define __fini_argmin(ami, arg, expr) 1
 #define __step_argmin(ami, arg, expr) 1
 
+#define __temp_while(expr)
 #define __init_while(expr) 1
 #define __test_while(expr) expr
 #define __prep_while(expr) 1
 #define __fini_while(expr) 1
 #define __step_while(expr) 1
 
+#define __temp_until(expr)
 #define __init_until(expr) 1
 #define __test_until(expr) !(expr)
 #define __prep_until(expr) 1
 #define __fini_until(expr) 1
 #define __step_until(expr) 1
 
+#define __temp_lockstep(...)
 #define __init_lockstep(...) __prog(__varexpand3(__init_first, __init_next,   \
                                                  __VA_ARGS__))
 #define __test_lockstep(...) __nd(__varexpand3(__test_first, __test_next,     \
@@ -260,6 +298,7 @@ function __loop_argmin(a, arga, b, argb)
 #define __step_lockstep(...) __prog(__varexpand3(__step_first, __step_next,   \
                                                  __VA_ARGS__))
 
+#define __temp_if(test, clause)
 #define __init_if(test, clause) __init_ ## clause
 #define __test_if(test, clause) !(test) || __test_ ## clause
 #define __prep_if(test, clause) (test) && __prep_ ## clause