tests/aux/json.sh: New file

2 files changed, 404 insertions, 1 deletions

diff --git a/tests/aux/json.sh b/tests/aux/json.sh
new file mode 100644
index 0000000..8f2cf9d
--- /dev/null
+++ b/tests/aux/json.sh
@@ -0,0 +1,402 @@
+# `json.sh`, a pure-shell JSON parser.
+#
+# Copied from <lib/json.sh> in repository <https://github.com/rcrowley/json.sh>.
+#
+# Copyright 2011 Richard Crowley. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     1.  Redistributions of source code must retain the above copyright
+#         notice, this list of conditions and the following disclaimer.
+#
+#     2.  Redistributions in binary form must reproduce the above
+#         copyright notice, this list of conditions and the following
+#         disclaimer in the documentation and/or other materials provided
+#         with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY RICHARD CROWLEY AS IS'' AND ANY EXPRESS
+# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL RICHARD CROWLEY OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+# THE POSSIBILITY OF SUCH DAMAGE.
+#
+# The views and conclusions contained in the software and documentation
+# are those of the authors and should not be interpreted as representing
+# official policies, either expressed or implied, of Richard Crowley.
+
+set -e
+
+# Most users will be happy with the default '/' separator that makes trees
+# of keys look like filesystem paths but that breaks down if keys can
+# contain slashes.  In that case, set `JSON_SEPARATOR` to desired character.
+[ -z "$JSON_SEPARATOR" ] && _J_S="/" || _J_S="$JSON_SEPARATOR"
+
+# File descriptor 3 is commandeered for debug output, which may end up being
+# forwarded to standard error.
+[ -z "$JSON_DEBUG" ] && exec 3>/dev/null || exec 3>&2
+
+# File descriptor 4 is commandeered for use as a sink for literal and
+# variable output of (inverted) sections that are not destined for standard
+# output because their condition is not met.
+exec 4>/dev/null
+
+# Consume standard input one character at a time to parse JSON.
+json() {
+
+	# Initialize the file descriptor to be used to emit characters.  At
+	# times this value will be 4 to send output to `/dev/null`.
+	_J_FD=1
+
+	# Initialize storage for the "pathname", the concatenation of all
+	# the keys in the tree at any point in time, the current state of
+	# the machine, and the state to which the machine returns after
+	# completing a key or value.
+	_J_PATHNAME="$_J_S" _J_STATE="whitespace" _J_STATE_DEFAULT="whitespace"
+
+	# IFS must only contain '\n' so as to be able to read space and tab
+	# characters from standard input one-at-a-time.  The easiest way to
+	# convince it to actually contain the correct byte, and only the
+	# correct byte, is to use a single-quoted literal newline.
+	IFS='
+'
+
+	# Consuming standard input one character at a time is quite a feat
+	# within the confines of POSIX shell.  Bash's `read` builtin has
+	# `-n` for limiting the number of characters consumed.  Here it is
+	# faked using `sed`(1) to place each character on its own line.
+	# The subtlety is that real newline characters are chomped so they
+	# must be indirectly detected by checking for zero-length
+	# characters, which is done as the character is emitted.
+	sed "
+		s/./&$(printf "\036")/g
+		s/\\\\/\\\\\\\\/g
+	" | tr "\036" "\n" | _json
+
+	# TODO Replace the original value of IFS.  Be careful if it's unset.
+
+}
+
+# Consume the one-character-per-line stream from `sed` via a state machine.
+# This function will be called recursively in subshell environments to
+# isolate values from their containing scope.
+#
+# The `read` builtin consumes one line at a time but by now each line
+# contains only a single character.
+_json() {
+	while read _J_C
+	do
+		_json_char
+		_J_PREV_C="$_J_C"
+	done
+}
+
+# Consume a single character as stored in `_J_C`.  This function is broken
+# out from `_json` so it may be called to reconsume a character as is
+# necessary following the end of any number since numbers do not have a
+# well-known ending in the grammar.
+#
+# The state machine implemented here follows very naturally from the
+# diagrams of the JSON grammar on <http://json.org>.
+_json_char() {
+	echo " _J_C: $_J_C (${#_J_C}), _J_STATE: $_J_STATE" >&3
+	case "$_J_STATE" in
+
+		# The machine starts in the "whitespace" state and learns
+		# from leading characters what state to enter next.  JSON's
+		# grammar doesn't contain any tokens that are ambiguous in
+		# their first character so the parser's job is relatively
+		# easier.
+		#
+		# Further whitespace characters are consumed and ignored.
+		#
+		# Arrays are unique in that their parsing rules are a strict
+		# superset of the rules in open whitespace.  When an opening
+		# bracket is encountered, the remainder of the array is
+		# parsed in a subshell which goes around again when a comma
+		# is encountered and exits back to the containing scope when
+		# the closing bracket is encountered.
+		#
+		# Objects are not parsed as a superset of open whitespace but
+		# they are parsed in a subshell to protect the containing scope.
+		"array-0"|"array-even"|"array-odd"|"whitespace")
+			case "$_J_STATE" in
+				"array-0")
+					case "$_J_C" in
+						"]") exit;;
+					esac;;
+				"array-even")
+					case "$_J_C" in
+						",")
+							_J_DIRNAME="${_J_PATHNAME%"$_J_S"*}"
+							[ "$_J_DIRNAME" = "$_J_S" ] && _J_DIRNAME=""
+							_J_BASENAME="${_J_PATHNAME##*"$_J_S"}"
+							_J_BASENAME="$(($_J_BASENAME + 1))"
+							_J_PATHNAME="$_J_DIRNAME$_J_S$_J_BASENAME"
+							_J_STATE="array-odd"
+							continue;;
+						"]") exit;;
+					esac;;
+			esac
+			case "$_J_C" in
+				"\"") _J_STATE="string" _J_V="";;
+				"-") _J_STATE="number-negative" _J_V="$_J_C";;
+				0) _J_STATE="number-leading-zero" _J_V="$_J_C";;
+				[1-9]) _J_STATE="number-leading-nonzero" _J_V="$_J_C";;
+				"[")
+					(
+						[ "$_J_PATHNAME" = "/" ] && _J_PATHNAME=""
+						_J_PATHNAME="$_J_PATHNAME/0"
+						_J_STATE="array-0" _J_STATE_DEFAULT="array-even"
+						_json
+					)
+					_J_STATE="$_J_STATE_DEFAULT" _J_V="";;
+				"f"|"t") _J_STATE="boolean" _J_V="$_J_C";;
+				"n") _J_STATE="null" _J_V="$_J_C";;
+				"{")
+					(
+						_J_STATE="object-0" _J_STATE_DEFAULT="object-even"
+						_json
+					)
+					_J_STATE="$_J_STATE_DEFAULT" _J_V="";;
+				"	"|""|" ") ;;
+				*) _json_die "syntax: $_J_PATHNAME";;
+			esac;;
+
+		# Boolean values are multicharacter literals but they're unique
+		# from their first character.  This means the eventual value is
+		# already known when the "boolean" state is entered so we can
+		# raise syntax errors as soon as the input goes south.
+		"boolean")
+			case "$_J_V$_J_C" in
+				"f"|"fa"|"fal"|"fals"|"t"|"tr"|"tru") _J_V="$_J_V$_J_C";;
+				"false"|"true")
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME boolean $_J_V$_J_C" >&$_J_FD;;
+				*) _json_die "syntax: $_J_PATHNAME boolean $_J_V$_J_C";;
+			esac;;
+
+		# Object values are relatively more complex than array values.
+		# They begin in the "object-0" state, which is almost but not
+		# quite a subset of the "whitespace" state for strings.  When
+		# a string is encountered it is parsed as usual but the parser
+		# is set to return to the "object-value" state afterward.
+		#
+		# As in the "whitespace" state, extra whitespace characters
+		# are consumed and ignored.
+		#
+		# The parser will return to this "object" state later to
+		# either consume a comma and go around again or exit the
+		# subshell in which this object has been parsed.
+		"object-0")
+			case "$_J_C" in
+				"\"")
+					_J_FD=4
+					_J_STATE="string"
+					_J_STATE_DEFAULT="object-value"
+					_J_V="";;
+				"}") exit;;
+				"	"|""|" ") ;;
+				*) _json_die "syntax: $_J_PATHNAME";;
+			esac;;
+
+		# "object-even" is like "object-0" but additionally commas are
+		# consumed to enforce the another key/value pair is coming.
+		"object-even")
+			case "$_J_C" in
+				"\"")
+					_J_FD=4
+					_J_STATE="string"
+					_J_STATE_DEFAULT="object-value"
+					_J_V="";;
+				",") _J_STATE="object-odd";;
+				"}") exit;;
+				"	"|""|" ") ;;
+				*) _json_die "syntax: $_J_PATHNAME";;
+			esac;;
+
+		# Object values have to return from whence they came.  They use
+		# the "object-exit" state to signal the last character consumed
+		# to the containing scope.
+		"object-exit") #exit;;
+			case "$_J_C" in
+				",") exit 101;;
+				"}") exit 102;;
+				*) exit 0;;
+			esac;;
+
+		# "object-even" is like "object-0" but cannot consume a closing
+		# brace because it has just consumed a comma.
+		"object-odd")
+			case "$_J_C" in
+				"\"")
+					_J_FD=4
+					_J_STATE="string"
+					_J_STATE_DEFAULT="object-value"
+					_J_V="";;
+				"	"|""|" ") ;;
+				*) _json_die "syntax: $_J_PATHNAME";;
+			esac;;
+
+		# After a string key has been consumed, the state machine
+		# progresses here where a colon and a value are parsed.  The
+		# value is parsed in a subshell so the pathname can have the
+		# key appended to it before the parser continues.
+		"object-value")
+			case "$_J_C" in
+				":")
+					_J_FD=1
+					(
+						[ "$_J_PATHNAME" = "/" ] && _J_PATHNAME=""
+						_J_PATHNAME="$_J_PATHNAME/$_J_V"
+						_J_STATE="whitespace"
+						_J_STATE_DEFAULT="object-exit"
+						_json
+					) || case "$?" in
+						101) _J_STATE="object-even" _J_C="," _json_char;;
+						102) _J_STATE="object-even" _J_C="}" _json_char;;
+					esac
+					_J_STATE="object-even";;
+				"	"|""|" ") ;;
+				*) _json_die "syntax: $_J_PATHNAME";;
+			esac;;
+
+		# Null values work exactly like boolean values.  See above.
+		"null")
+			case "$_J_V$_J_C" in
+				"n"|"nu"|"nul") _J_V="$_J_V$_J_C";;
+				"null")
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME null null" >&$_J_FD;;
+				*) _json_die "syntax: $_J_PATHNAME null $_J_V$_J_C";;
+			esac;;
+
+		# Numbers that encounter a '.' become floating point and may
+		# continue consuming digits forever or may become
+		# scientific-notation.  Any other character sends the parser
+		# back to its default state.
+		"number-float")
+			case "$_J_C" in
+				[0-9]) _J_V="$_J_V$_J_C";;
+				"E"|"e") _J_STATE="number-sci" _J_V="$_J_V$_J_C";;
+				*)
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME number $_J_V" >&$_J_FD
+					_json_char;;
+			esac;;
+
+		# This is an entrypoint into parsing a number, used when
+		# the first digit consumed is non-zero.  From here, a number
+		# may continue on a positive integer, become a floating-point
+		# number by consuming a '.', or become scientific-notation by
+		# consuming an 'E' or 'e'.  Any other character sends the
+		# parser back to its default state.
+		"number-leading-nonzero")
+			case "$_J_C" in
+				".") _J_STATE="number-float" _J_V="$_J_V$_J_C";;
+				[0-9]) _J_V="$_J_V$_J_C";;
+				"E"|"e") _J_STATE="number-sci" _J_V="$_J_V$_J_C";;
+				*)
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME number $_J_V" >&$_J_FD
+					_json_char;;
+			esac;;
+
+		# This is an entrypoint into parsing a number, used when
+		# the first digit consumed is zero.  From here, a number
+		# may remain zero, become a floating-point number by
+		# consuming a '.', or become scientific-notation by consuming
+		# an 'E' or 'e'.  Any other character sends the parser back
+		# to its default state.
+		"number-leading-zero")
+			case "$_J_C" in
+				".") _J_STATE="number-float" _J_V="$_J_V$_J_C";;
+				[0-9]) _json_die "syntax: $_J_PATHNAME number $_J_V$_J_C";;
+				"E"|"e") _J_STATE="number-sci" _J_V="$_J_V$_J_C";;
+				*)
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME number $_J_V" >&$_J_FD
+					_json_char;;
+			esac;;
+
+		# This is an entrypoint into parsing a number, used when
+		# the first character consumed is a '-'.  From here, a number
+		# may progress to the "number-leading-nonzero" or
+		# "number-leading-zero" states.  Any other character sends
+		# the parser back to its default state.
+		"number-negative")
+			case "$_J_C" in
+				0) _J_STATE="number-leading-zero" _J_V="$_J_V$_J_C";;
+				[1-9])
+					_J_STATE="number-leading-nonzero"
+					_J_V="$_J_V$_J_C";;
+				*)
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME number $_J_V" >&$_J_FD
+					_json_char;;
+			esac;;
+
+		# Numbers that encounter an 'E' or 'e' become
+		# scientific-notation and consume digits, optionally prefixed
+		# by a '+' or '-', forever.  The actual consumption is
+		# delegated to the "number-sci-neg" and "number-sci-pos"
+		# states.  Any other character immediately following the 'E'
+		# or 'e' is a syntax error.
+		"number-sci")
+			case "$_J_C" in
+				"+") _J_STATE="number-sci-pos" _J_V="$_J_V$_J_C";;
+				"-") _J_STATE="number-sci-neg" _J_V="$_J_V$_J_C";;
+				[0-9]) _J_STATE="number-sci-pos" _J_V="$_J_V$_J_C";;
+				*) _json_die "syntax: $_J_PATHNAME number $_J_V$_J_C";;
+			esac;;
+
+		# Once in these states, numbers may consume digits forever.
+		# Any other character sends the parser back to its default
+		# state.
+		"number-sci-neg"|"number-sci-pos")
+			case "$_J_C" in
+				[0-9]) _J_V="$_J_V$_J_C";;
+				*)
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME number $_J_V" >&$_J_FD
+					_json_char;;
+			esac;;
+
+		# Strings aren't as easy as they look.  JSON supports several
+		# escape sequences that require the state machine to keep a
+		# history of its input.  Basic backslash/newline/etc. escapes
+		# are simple because they only require one character of
+		# history.  Unicode codepoint escapes require more.  The
+		# strategy there is to add states to the machine.
+		#
+		# TODO It'd be nice to decode all escape sequences, including
+		# Unicode codepoints but that would definitely ruin the
+		# line-oriented thing we've got goin' on.
+		"string")
+			case "$_J_PREV_C$_J_C" in
+				"\\\""|"\\/"|"\\\\") _J_V="$_J_V$_J_C";;
+				"\\b"|"\\f"|"\\n"|"\\r")  _J_V="$_J_V\\\\$_J_C";;
+				"\\u") _J_V="$_J_V\\\\$_J_C";;
+				*"\"")
+					_J_STATE="$_J_STATE_DEFAULT"
+					echo "$_J_PATHNAME string $_J_V" >&$_J_FD;;
+				*"\\") ;;
+				*) _J_V="$_J_V$_J_C";;
+			esac;;
+
+	esac
+}
+
+# Print an error message and GTFO.  The message is the concatenation
+# of all the arguments to this function.
+_json_die() {
+	echo "json.sh: $*" >&2
+	exit 1
+}
diff --git a/tests/local.mk b/tests/local.mk
index 6d7980c..288b9ad 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -9,4 +9,5 @@ SH_LOG_DRIVER = \
 EXTRA_DIST += \
 	$(TESTS) \
 	build-aux/tap-driver.sh \
-	tests/aux/tap-functions.sh
+	tests/aux/tap-functions.sh \
+	tests/aux/json.sh