eshld/eshrt: Encode stack in vars with a stack pointer

String manipulations are slow and require fork()ing for sed to
escape/encode input data.

1 files changed, 29 insertions, 44 deletions

diff --git a/eshld/eshrt.esh b/eshld/eshrt.esh
index bcc69b4..ad03b09 100644
--- a/eshld/eshrt.esh
+++ b/eshld/eshrt.esh
@@ -24,8 +24,7 @@ eshrtbegin()
 __ESC="$(printf '\033.')"; __ESC="${__ESC%.}"
  __RS="$(printf '\036.')";  __RS="${__RS%.}"
  __US="$(printf '\037.')";  __US="${__US%.}"
-__fn_stack=''
-__fn_frame=''
+__sp=0
 __fn_name=''
 __fn_tu=''
 __fn_vars=''
@@ -35,49 +34,35 @@ __prev_tu=''
 __prev_vars=''
 __var=''
 __val=''
+__fn_frame=0
 __fn_begin_hooks=''
 __fn_end_hooks=''
 __init_funcs=''
 
-__fn_stack_push()
+__sp_inc()
 {
-	__fn_stack="${__fn_stack}${__RS}${__fn_frame}"
+	__sp=$((${__sp} + 1))
 }
 
-__fn_stack_peek()
+__sp_dec()
 {
-	__fn_frame="${__fn_stack##*${__RS}}"
+	__sp=$((${__sp} - 1))
 }
 
-__fn_stack_pop()
+__frame_set()
 {
-	__fn_stack_peek
-	__fn_stack="${__fn_stack%${__RS}*}"
+	eval "__frame_${__sp}_name=\${__fn_name}"
+	eval "__frame_${__sp}_tu=\${__fn_tu}"
+	eval "__frame_${__sp}_vars=\${__fn_vars}"
+	eval "__frame_${__sp}_var_vals=\${__fn_var_vals}"
 }
 
-__fn_frame_encode()
+__frame_get()
 {
-	# RS and US in frame variable values must be encoded.
-	__fn_var_vals="$(printf '%s' "${__fn_var_vals}" | sed "
-		s|${__ESC}|${__ESC}0|g;
-		s|${__RS}|${__ESC}1|g; s|${__US}|${__ESC}2|g;
-		")"
-	__fn_frame="${__fn_name}${__US}${__fn_tu}"
-	__fn_frame="${__fn_frame}${__US}${__fn_vars}${__US}${__fn_var_vals}"
-}
-
-__fn_frame_decode()
-{
-	__fn_name="${__fn_frame%%${__US}*}"
-	__fn_frame="${__fn_frame#*${__US}}"
-	__fn_tu="${__fn_frame%%${__US}*}"
-	__fn_frame="${__fn_frame#*${__US}}"
-	__fn_vars="${__fn_frame%%${__US}*}"
-	__fn_var_vals="${__fn_frame#*${__US}}"
-	__fn_var_vals="$(printf '%s' "${__fn_var_vals}" | sed "
-		s|${__ESC}0|${__ESC}|g;
-		s|${__ESC}1|${__RS}|g; s|${__ESC}2|${__US}|g;
-		")"
+	eval "__fn_name=\${__frame_${__sp}_name}"
+	eval "__fn_tu=\${__frame_${__sp}_tu}"
+	eval "__fn_vars=\${__frame_${__sp}_vars}"
+	eval "__fn_var_vals=\${__frame_${__sp}_var_vals}"
 }
 
 __fn_ctxsw()
@@ -135,19 +120,18 @@ __fn_start()
 	__prev_vars="${__fn_vars}"
 
 	# Update local vars in stack.
-	__fn_stack_pop
-	__fn_vars="${__prev_vars}"
 	__fn_update_vars
-	__fn_frame_encode
-	__fn_stack_push
+	__frame_set
+
+	# Set stack pointer.
+	__sp_inc
 
 	# New state.
 	__fn_name="${2}"
 	__fn_tu="${1}"
 	__fn_vars=
 	__fn_var_vals=
-	__fn_frame_encode
-	__fn_stack_push
+	__frame_set
 
 	# Switch.
 	__fn_ctxsw
@@ -161,14 +145,14 @@ __fn_end()
 	done
 
 	# Old state.
-	__fn_stack_pop
-	__fn_frame_decode
 	__prev_tu="${__fn_tu}"
 	__prev_vars="${__fn_vars}"
 
+	# Set stack pointer.
+	__sp_dec
+
 	# New state.
-	__fn_stack_peek
-	__fn_frame_decode
+	__frame_get
 
 	# Switch.
 	__fn_ctxsw
@@ -190,9 +174,10 @@ __tu_end()
 
 __stack_trace()
 {
-	IFS="${__RS}"
-	for __fn_frame in ${__fn_stack#${__RS}}; do
-		printf '%s\n' "${__fn_frame%%${__US}*}"
+	__fn_frame=0
+	while [ ${__fn_frame} -le ${__sp} ]; do
+		eval "printf '%s\n' \"\${__frame_${__fn_frame}_name}\""
+		__fn_frame=$((${__fn_frame} + 1))
 	done
 }