eshld: Add runtime library

4 files changed, 257 insertions, 24 deletions

diff --git a/eshld/Makefile b/eshld/Makefile
index 03b3c3b..a768ca6 100644
--- a/eshld/Makefile
+++ b/eshld/Makefile
@@ -1,6 +1,7 @@
 SOURCES = \
 	main.esh \
-	link.esh
+	link.esh \
+	eshrt.esh
 OBJECTS = $(SOURCES:.esh=.sh)
 
 all: eshld
diff --git a/eshld/eshrt.esh b/eshld/eshrt.esh
new file mode 100644
index 0000000..0a6fdb7
--- /dev/null
+++ b/eshld/eshrt.esh
@@ -0,0 +1,248 @@
+# Eggshell Linker runtime library
+#
+# Copyright (C) 2016  Patrick "P. J." McDermott
+#
+# This file is part of the Eggshell Linker.
+#
+# The Eggshell Linker is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation, either version 3 of
+# the License, or (at your option) any later version.
+#
+# The Eggshell Linker is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+# of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with the Eggshell Linker  If not, see
+# <http://www.gnu.org/licenses/>.
+
+eshrtbegin()
+{
+	cat <<-'EOF'
+__ESC="$(printf '\033.')"; __ESC="${__ESC%.}"
+ __RS="$(printf '\036.')";  __RS="${__RS%.}"
+ __US="$(printf '\037.')";  __US="${__US%.}"
+__fn_stack=''
+__fn_frame=''
+__fn_name=''
+__fn_tu=''
+__fn_vars=''
+__fn_var_vals=''
+__fn=''
+__prev_tu=''
+__prev_vars=''
+__var=''
+__val=''
+__init_funcs=''
+
+__fn_stack_push()
+{
+	__fn_stack="${__fn_stack}${__RS}${__fn_frame}"
+}
+
+__fn_stack_peek()
+{
+	__fn_frame="${__fn_stack##*${__RS}}"
+}
+
+__fn_stack_pop()
+{
+	__fn_stack_peek
+	__fn_stack="${__fn_stack%${__RS}*}"
+}
+
+__fn_frame_encode()
+{
+	# RS and US in frame variable values must be encoded.
+	__fn_var_vals="$(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|${__US}|g;
+		")"
+}
+
+__fn_ctxsw()
+{
+	unset IFS
+	case "${__prev_tu}" in
+		${__fn_tu});;
+		?*)
+			# Unset static variables and functions from previous TU.
+			eval "unset \${__${__prev_tu}_static_vars}"
+			for __fn in $(eval printf '%s' \
+					"\"\${__${__prev_tu}_static_fns}\""); do
+				unset -f "${__fn%:*}"
+			done
+	;; esac
+	case "${__fn_tu}" in
+		${__prev_tu});;
+		?*)
+			# Set static variables and function for the current TU.
+			eval "$(eval printf '%s' "\"$(eval printf '%s' \
+				"'\${__${__fn_tu}_static_var_vals}'")\"")"
+			for __fn in $(eval printf '%s' \
+					"\"\${__${__fn_tu}_static_fns}\""); do
+				eval "${__fn%:*}() { ${__fn#*:}; }"
+			done
+	;; esac
+	unset ${__prev_vars}
+	eval "${__fn_var_vals}"
+}
+
+__fn_update_vars()
+{
+	for __var in ${__fn_vars}; do
+		__val="$(eval "printf '%s' \"\${${__var}}\"" | \
+			sed "s|'|'\\\\''|g;")"
+		__fn_var_vals="${__fn_var_vals} ${__var}='${__val}'"
+	done
+}
+
+__fn_start()
+{
+	# Old state.
+	__prev_tu="${__fn_tu}"
+	__prev_vars="${__fn_vars}"
+
+	# Update local vars in stack.
+	__fn_stack_pop
+	__fn_vars="${__prev_vars}"
+	__fn_update_vars
+	__fn_frame_encode
+	__fn_stack_push
+
+	# New state.
+	__fn_name="${2}"
+	__fn_tu="${1}"
+	__fn_vars=
+	__fn_var_vals=
+	__fn_frame_encode
+	__fn_stack_push
+
+	# Switch.
+	__fn_ctxsw
+}
+
+__fn_end()
+{
+	# Old state.
+	__fn_stack_pop
+	__fn_frame_decode
+	__prev_tu="${__fn_tu}"
+	__prev_vars="${__fn_vars}"
+
+	# New state.
+	__fn_stack_peek
+	__fn_frame_decode
+
+	# Switch.
+	__fn_ctxsw
+}
+
+__tu_end()
+{
+	# Save TU static vars.
+	for __var in $(eval "printf '%s' \"\${__${__tu}_static_vars}\""); do
+		__val="$(eval "printf '%s' \"\${${__var}}\"" | \
+			sed "s|'|'\\\\''|g")"
+		eval "__${__tu}_static_var_vals=\"\${__${__tu}_static_var_vals}\
+			${__var}='\${__val}'\""
+		unset ${__var}
+	done
+
+	__tu=''
+}
+
+__stack_trace()
+{
+	IFS="${__RS}"
+	for __fn_frame in ${__fn_stack#${__RS}}; do
+		printf '%s\n' "${__fn_frame%%${__US}*}"
+	done
+}
+
+__local()
+{
+	for __var in "${@}"; do
+		case "${__var}" in
+			*=*)
+				__val="${__var#*=}"
+				__var="${__var%%=*}"
+				;;
+			*)
+				__val=''
+				;;
+		esac
+		case "${__var}" in [!A-Za-z_]* | *[!0-9A-Za-z_]*)
+			printf 'Syntax error: %s %s\n' \
+				'illegal static variable name:' "${__var}" >&2
+			exit 1
+		;; esac
+		eval "${__var}=\${__val}"
+		__fn_vars="${__fn_vars} ${__var}"
+	done
+}
+
+static()
+{
+	case "${__tu}" in '')
+		printf 'Error: Cannot declare static variables in functions' >&2
+		exit 1
+	;; esac
+	for __var in "${@}"; do
+		case "${__var}" in
+			*=*)
+				__val="${__var#*=}"
+				__var="${__var%%=*}"
+				;;
+			*)
+				__val=''
+				;;
+		esac
+		case "${__var}" in [!A-Za-z_]* | *[!0-9A-Za-z_]*)
+			printf 'Syntax error: %s %s\n' \
+				'illegal static variable name:' "${__var}" >&2
+			exit 1
+		;; esac
+		eval "${__var}=\${__val}"
+		eval "__${__tu}_static_vars=\"\${__${__tu}_static_vars} \
+			${__var}\""
+	done
+}
+
+__init()
+{
+	__init_funcs="${__init_funcs} ${1}"
+}
+EOF
+}
+
+eshrtend()
+{
+	local entry="${1}"
+	shift 1
+
+	cat <<-'EOF'
+for __func in ${__init_funcs}; do
+	${__func}
+done
+EOF
+	printf '%s "${@}"\n' "${entry_point}"
+}
diff --git a/eshld/link.esh b/eshld/link.esh
index d01fc4d..d674821 100644
--- a/eshld/link.esh
+++ b/eshld/link.esh
@@ -1,6 +1,6 @@
-# Eggshell Linker entry point
+# Eggshell Linker program linking functions
 #
-# Copyright (C) 2015  Patrick "P. J." McDermott
+# Copyright (C) 2015, 2016  Patrick "P. J." McDermott
 #
 # This file is part of the Eggshell Linker.
 #
@@ -50,20 +50,11 @@ link_begin()
 		die 'Cannot open file "%s"' "${output}~"
 	fi
 
-	# Write magic number and interpreter path.
+	# Add a magic number with interpreter path and the runtime library.
 	if ${make_executable}; then
 		printf '#!%s\n' "${interpreter}" >&3
+		eshrtbegin >&3
 	fi
-
-	# Write __init() function.
-	cat >&3 <<-'EOF'
-		__init_funcs=''
-		__init()
-		{
-			__init_funcs="${__init_funcs} ${1}"
-		}
-		EOF
-
 }
 
 link_file()
@@ -77,16 +68,9 @@ link_file()
 
 link_end()
 {
-	# Add call to init functions.
-	cat >&3 <<-'EOF'
-		for __func in ${__init_funcs}; do
-			${__func}
-		done
-		EOF
-
-	# Add call to entry point.
+	# Add calls to __init functions and the entry point.
 	if ${make_executable}; then
-		printf '%s "${@}"\n' "${entry_point}" >&3
+		eshrtend "${entry_point}" >&3
 	fi
 
 	# Close output file, make it executable, and set its name.
diff --git a/eshld/main.esh b/eshld/main.esh
index 775179f..24cdae1 100644
--- a/eshld/main.esh
+++ b/eshld/main.esh
@@ -1,6 +1,6 @@
 # Eggshell Linker entry point
 #
-# Copyright (C) 2015  Patrick "P. J." McDermott
+# Copyright (C) 2015, 2016  Patrick "P. J." McDermott
 #
 # This file is part of the Eggshell Linker.
 #