1 files changed, 591 insertions, 0 deletions
diff --git a/eshtrans/frontend/parser.esh b/eshtrans/frontend/parser.esh
new file mode 100644
index 0000000..d49fa77
--- /dev/null
+++ b/eshtrans/frontend/parser.esh
@@ -0,0 +1,591 @@
+# Eggshell parser
+#
+# Copyright (C) 2016  Patrick "P. J." McDermott
+#
+# This file is part of the Eggshell Compiler.
+#
+# The Eggshell Compiler 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 Compiler 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 Compiler.  If not, see
+# <http://www.gnu.org/licenses/>.
+
+ptrace=false
+
+#
+# Function tracing
+#
+
+ptrace_begn()
+{
+	local fn="${1}"
+	shift 1
+
+	if ${ptrace}; then
+		printf 'TRACE: BEGN %s()\n' "${fn}" >&2
+	fi
+}
+
+ptrace_pass()
+{
+	local fn="${1}"
+	shift 1
+
+	if ${ptrace}; then
+		printf 'TRACE: PASS %s()\n' "${fn}" >&2
+	fi
+}
+
+ptrace_fail()
+{
+	local fn="${1}"
+	shift 1
+
+	if ${ptrace}; then
+		printf 'TRACE: FAIL %s()\n' "${fn}" >&2
+	fi
+}
+
+#
+# Parser
+#
+
+complete_command()
+{
+	if list; then
+		separator
+		return 0
+	fi
+	return 1
+}
+
+list()
+{
+	ptrace_begn list
+	if and_or; then
+		while separator && and_or; do
+			:
+		done
+		ptrace_pass list
+		return 0
+	fi
+	ptrace_fail list
+	return 1
+}
+
+and_or()
+{
+	ptrace_begn and_or
+	if pipeline; then
+		while accept T_AND_IF || accept T_OR_IF; do
+			if ! linebreak || ! pipeline; then
+				ptrace_fail and_or
+				return 1
+			fi
+		done
+		ptrace_pass and_or
+		return 0
+	fi
+	ptrace_fail and_or
+	return 1
+}
+
+pipeline()
+{
+	ptrace_begn pipeline
+	accept T_BANG
+	if pipe_sequence; then
+		ptrace_pass pipeline
+		return 0
+	fi
+	ptrace_fail pipeline
+	return 1
+}
+
+pipe_sequence()
+{
+	ptrace_begn pipe_sequence
+	if command; then
+		while accept T_PIPE; do
+			if ! linebreak || ! command; then
+				ptrace_fail pipe_sequence
+				return 1
+			fi
+		done
+		ptrace_pass pipe_sequence
+		return 0
+	fi
+	ptrace_fail pipe_sequence
+	return 1
+}
+
+command()
+{
+	ptrace_begn command
+	if simple_command; then
+		ptrace_pass command
+		return 0
+	elif compound_command; then
+		redirect_list
+		ptrace_pass command
+		return 0
+	fi
+	ptrace_fail command
+	return 1
+}
+
+compound_command()
+{
+	ptrace_begn compound_command
+	if brace_group; then
+		ptrace_pass compound_command
+		return 0
+	elif subshell; then
+		ptrace_pass compound_command
+		return 0
+	elif for_clause; then
+		ptrace_pass compound_command
+		return 0
+	elif case_clause; then
+		ptrace_pass compound_command
+		return 0
+	elif if_clause; then
+		ptrace_pass compound_command
+		return 0
+	elif while_clause; then
+		ptrace_pass compound_command
+		return 0
+	elif until_clause; then
+		ptrace_pass compound_command
+		return 0
+	fi
+	ptrace_fail compound_command
+	return 1
+}
+
+subshell()
+{
+	ptrace_begn subshell
+	if accept T_LPAREN && compound_list && expect T_RPAREN; then
+		ptrace_pass subshell
+		return 0
+	fi
+	ptrace_fail subshell
+	return 1
+}
+
+compound_list()
+{
+	ptrace_begn compound_list
+	newline_list
+	if term; then
+		separator
+		ptrace_pass compound_list
+		return 0
+	fi
+	ptrace_fail compound_list
+	return 1
+}
+
+term()
+{
+	ptrace_begn term
+	if and_or; then
+		while separator; do
+			and_or
+		done
+		ptrace_pass term
+		return 0
+	fi
+	ptrace_fail term
+	return 1
+}
+
+for_clause()
+{
+	ptrace_begn for_clause
+	if accept T_FOR; then
+		if expect T_NAME && linebreak; then
+			if accept T_IN; then
+				wordlist
+				if ! sequential_sep; then
+					ptrace_fail for_clause
+					return 1
+				fi
+			fi
+			if do_group; then
+				ptrace_pass for_clause
+				return 0
+			fi
+		fi
+	fi
+	ptrace_fail for_clause
+	return 1
+}
+
+wordlist()
+{
+	ptrace_begn wordlist
+	if accept T_WORD; then
+		while accept T_WORD; do :; done
+		ptrace_pass wordlist
+		return 0
+	fi
+	ptrace_fail wordlist
+	return 1
+}
+
+case_clause()
+{
+	if accept T_CASE; then
+		if expect T_WORD && linebreak && expect T_IN && linebreak; then
+			case_list || case_list_ns
+			expect T_ESAC
+			return 0
+		fi
+	fi
+	return 1
+}
+
+case_list_ns()
+{
+	if case_list && case_item_ns; then
+		return 0
+	elif case_item_ns; then
+		return 0
+	fi
+	return 1
+}
+
+case_list()
+{
+	if case_item; then
+		while case_item; do
+			:
+		done
+		return 0
+	fi
+	return 1
+}
+
+case_item_ns()
+{
+	accept T_LPAREN
+	if pattern && expect RPAREN; then
+		compound_list
+		if linebreak; then
+			return 0
+		fi
+	fi
+	return 1
+}
+
+case_item()
+{
+	accept T_LPAREN
+	if pattern && expect T_RPAREN; then
+		if compound_list || linebreak; then
+			if expect T_DSEMI && linebreak; then
+				return 0
+			fi
+		fi
+	fi
+	return 1
+}
+
+pattern()
+{
+	if accept T_CMDNAME; then
+		while accept T_PIPE; do
+			expect T_WORD
+		done
+		return 0
+	fi
+	return 1
+}
+
+if_clause()
+{
+	if accept T_IF; then
+		if compound_list && expect T_THEN && compound_list; then
+			else_part
+			expect T_FI
+			return 0
+		fi
+	fi
+	return 1
+}
+
+else_part()
+{
+	while accept T_ELIF; do
+		if compound_list && expect T_THEN && compound_list; then
+			continue
+		fi
+		return 1
+	done
+	if accept T_ELSE; then
+		if compound_list; then
+			return 0
+		fi
+	fi
+	return 1
+}
+
+while_clause()
+{
+	if accept T_WHILE; then
+		if compound_list && do_group; then
+			return 0
+		fi
+	fi
+	return 1
+}
+
+until_clause()
+{
+	if accept T_UNTIL; then
+		if compound_list && do_group; then
+			return 0
+		fi
+	fi
+	return 1
+}
+
+function_body()
+{
+	ptrace_begn function_body
+	if compound_command; then
+		redirect_list
+		ptrace_pass function_body
+		return 0
+	fi
+	ptrace_fail function_body
+	return 1
+}
+
+brace_group()
+{
+	ptrace_begn brace_group
+	if accept T_LBRACE && compound_list && expect T_RBRACE; then
+		ptrace_pass brace_group
+		return 0
+	fi
+	ptrace_fail brace_group
+	return 1
+}
+
+do_group()
+{
+	ptrace_begn do_group
+	if accept T_DO && compound_list && expect T_DONE; then
+		ptrace_pass do_group
+		return 0
+	fi
+	ptrace_fail do_group
+	return 1
+}
+
+simple_command()
+{
+	ptrace_begn simple_command
+	if cmd_prefix; then
+		if cmd_word; then
+			cmd_suffix
+		fi
+		ptrace_pass simple_command
+		return 0
+	elif accept T_FNAME; then
+		if accept T_LPAREN; then
+			expect T_RPAREN
+			if linebreak && function_body; then
+				ptrace_pass simple_command
+				return 0
+			fi
+		else
+			cmd_suffix
+			ptrace_pass simple_command
+			return 0
+		fi
+	elif cmd_name; then
+		cmd_suffix
+		ptrace_pass simple_command
+		return 0
+	fi
+	ptrace_fail simple_command
+	return 1
+}
+
+cmd_name()
+{
+	ptrace_begn cmd_name
+	# TODO: Assignment
+	if accept T_CMDNAME; then
+		ptrace_pass cmd_name
+		return 0
+	fi
+	ptrace_fail cmd_name
+	return 1
+}
+
+cmd_word()
+{
+	ptrace_begn cmd_word
+	# TODO: Assignment
+	if accept T_WORD; then
+		ptrace_pass cmd_word
+		return 0
+	fi
+	ptrace_fail cmd_word
+	return 1
+}
+
+cmd_prefix()
+{
+	ptrace_begn cmd_prefix
+	if io_redirect || accept T_ASSIGNMENT_WORD; then
+		while io_redirect || accept T_ASSIGNMENT_WORD; do
+			:
+		done
+		ptrace_pass cmd_prefix
+		return 0
+	fi
+	ptrace_fail cmd_prefix
+	return 1
+}
+
+cmd_suffix()
+{
+	ptrace_begn cmd_suffix
+	if io_redirect || accept T_WORD; then
+		while io_redirect || accept T_WORD; do
+			:
+		done
+		ptrace_pass cmd_suffix
+		return 0
+	fi
+	ptrace_fail cmd_suffix
+	return 1
+}
+
+redirect_list()
+{
+	ptrace_begn redirect_list
+	if io_redirect; then
+		while io_redirect; do
+			:
+		done
+		ptrace_pass redirect_list
+		return 0
+	fi
+	ptrace_fail redirect_list
+	return 1
+}
+
+io_redirect()
+{
+	ptrace_begn io_redirect
+	if io_file || io_here; then
+		ptrace_pass io_redirect
+		return 0
+	fi
+	ptrace_fail io_redirect
+	return 1
+}
+
+io_file()
+{
+	if accept T_LESS || accept T_LESSAND || accept T_GREAT || \
+			accept T_GREATAND || accept T_DGREAT || \
+			accept T_LESSGREAT || accept T_CLOBBER; then
+		if filename; then
+			return 0
+		fi
+	fi
+	return 1
+}
+
+filename()
+{
+	if accept T_WORD; then
+		return 0
+	fi
+	return 1
+}
+
+io_here()
+{
+	if accept T_DLESS || accept T_DLESSDASH; then
+		if here_end; then
+			return 0
+		fi
+	fi
+	return 1
+}
+
+here_end()
+{
+	if accept T_WORD; then
+		return 0
+	fi
+	return 1
+}
+
+newline_list()
+{
+	if accept T_NEWLINE; then
+		while accept T_NEWLINE; do
+			:
+		done
+		return 0
+	fi
+	return 1
+}
+
+linebreak()
+{
+	newline_list
+	return 0
+}
+
+separator_op()
+{
+	if accept T_AND || accept T_SEMI; then
+		return 0
+	fi
+	return 1
+}
+
+separator()
+{
+	if separator_op && linebreak; then
+		return 0
+	elif newline_list; then
+		return 0
+	fi
+	return 1
+}
+
+sequential_sep()
+{
+	ptrace_begn sequential_sep
+	if accept T_SEMI; then
+		if linebreak; then
+			ptrace_pass sequential_sep
+			return 0
+		fi
+	elif newline_list; then
+		ptrace_pass sequential_sep
+		return 0
+	fi
+	ptrace_fail sequential_sep
+	return 1
+}