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json-parser

@@ -0,0 +1,189 @@
+#!/usr/bin/env bash
+
+function output_entry() {
+	echo "$1=$2"
+}
+
+function parse_array() {
+	local current_path="${1:+$1.}$2"
+	local current_scope="root"
+	local current_index=0
+
+	while [ "$chars_read" -lt "$INPUT_LENGTH" ]; do
+		[ "$preserve_current_char" == "0" ] && chars_read=$((chars_read+1)) && read -r -s -n 1 c
+		preserve_current_char=0
+		c=${c:-' '}
+
+		case "$current_scope" in
+			"root") # Waiting for new object or value
+				case "$c" in
+					'{')
+						parse_object "$current_path" "$current_index"
+						current_scope="entry_separator"
+						;;
+					']')
+						return
+						;;
+					[\"tfTF\-0-9])
+						preserve_current_char=1 # Let the parse value function decide what kind of value this is
+						parse_value "$current_path" "$current_index"
+						preserve_current_char=1 # Parse value has terminated with a separator or an array end, but we can handle this only in the next while iteration
+						current_scope="entry_separator"
+						;;
+						
+				esac
+				;;
+			"entry_separator")
+				[ "$c" == "," ] && current_index=$((current_index+1)) && current_scope="root"
+				[ "$c" == "]" ] && return
+				;;
+		esac
+	done
+}
+
+function parse_value() {
+	local current_path="${1:+$1.}$2"
+	local current_scope="root"
+
+	while [ "$chars_read" -lt "$INPUT_LENGTH" ]; do
+		[ "$preserve_current_char" == "0" ] && chars_read=$((chars_read+1)) && read -r -s -n 1 c
+		preserve_current_char=0
+		c=${c:-' '}
+
+		case "$current_scope" in
+			"root") # Waiting for new string, number or boolean
+				case "$c" in
+					'"') # String begin
+						current_scope="string"
+						current_varvalue=""
+						;;
+					[\-0-9]) # Number begin
+						current_scope="number"
+						current_varvalue="$c"
+						;;
+					[tfTF]) # True or false begin
+						current_scope="boolean"
+						current_varvalue="$c"
+						;;
+					"[") # Array begin
+						parse_array "" "$current_path"
+						return
+						;;
+					"{") # Object begin
+						parse_object "" "$current_path"
+						return
+				esac
+				;;
+			"string") # Waiting for string end
+				case "$c" in
+					'"') # String end if not in escape mode, normal character otherwise
+						[ "$current_escaping" == "0" ] && output_entry "$current_path" "$current_varvalue" && return
+						[ "$current_escaping" == "1" ] && current_varvalue="$current_varvalue$c" && current_escaping=0
+						;;
+					'\') # Escape character, entering or leaving escape mode
+						current_escaping=$((1-current_escaping))
+						current_varvalue="$current_varvalue$c"
+						;;
+					*) # Any other string character
+						current_escaping=0
+						current_varvalue="$current_varvalue$c"
+						;;
+				esac
+				;;
+			"number") # Waiting for number end
+				case "$c" in
+					[,\]}]) # Separator or array end or object end
+						output_entry "$current_path" "$current_varvalue"
+						preserve_current_char=1 # The caller needs to handle this char
+						return
+						;;
+					[\-0-9.]) # Number can only contain digits, dots and a sign
+						current_varvalue="$current_varvalue$c"
+						;;
+					# Ignore everything else
+				esac
+				;;
+			"boolean") # Waiting for boolean to end
+				case "$c" in
+					[,\]}]) # Separator or array end or object end
+						output_entry "$current_path" "$current_varvalue"
+						preserve_current_char=1 # The caller needs to handle this char
+						return
+						;;
+					[a-zA-Z]) # No need to do some strict checking, we do not want to validate the incoming json data
+						current_varvalue="$current_varvalue$c"
+						;;
+					# Ignore everything else
+				esac
+				;;
+		esac
+	done
+}
+
+function parse_object() {
+	local current_path="${1:+$1.}$2"
+	local current_scope="root"
+
+	while [ "$chars_read" -lt "$INPUT_LENGTH" ]; do
+		[ "$preserve_current_char" == "0" ] && chars_read=$((chars_read+1)) && read -r -s -n 1 c
+		preserve_current_char=0
+		c=${c:-' '}
+
+		case "$current_scope" in
+			"root") # Waiting for new field or object end
+				[ "$c" == "}" ]  && return
+				[ "$c" == "\"" ] && current_scope="varname" && current_varname="" && current_escaping=0
+				;;
+			"varname") # Reading the field name
+				case "$c" in
+					'"') # String end if not in escape mode, normal character otherwise
+						[ "$current_escaping" == "0" ] && current_scope="key_value_separator"
+						[ "$current_escaping" == "1" ] && current_varname="$current_varname$c"
+						;;
+					'\') # Escape character, entering or leaving escape mode
+						current_escaping=$((1-current_escaping))
+						current_varname="$current_varname$c"
+						;;
+					*) # Any other string character
+						current_escaping=0
+						current_varname="$current_varname$c"
+						;;
+				esac
+				;;
+			"key_value_separator") # Waiting for the key value separator (:)
+				[ "$c" == ":" ] && parse_value "$current_path" "$current_varname" && current_scope="field_separator"
+				;;
+			"field_separator") # Waiting for the field separator (,)
+				[ "$c" == ',' ] && current_scope="root"
+				[ "$c" == '}' ] && return
+				;;
+		esac
+	done
+}
+
+function parse() {
+	chars_read=0
+	preserve_current_char=0
+
+	while [ "$chars_read" -lt "$INPUT_LENGTH" ]; do
+		read -r -s -n 1 c
+		c=${c:-' '}
+		chars_read=$((chars_read+1))
+
+		# A valid JSON string consists of exactly one object
+		[ "$c" == "{" ] && parse_object "" "" && return
+        # ... or one array
+        [ "$c" == "[" ] && parse_array "" "" && return
+        
+	done
+}
+
+if [ -z "$@" ]; then
+	INPUT=$(cat -)
+else
+	INPUT=$(echo "$@")
+fi
+
+INPUT_LENGTH="${#INPUT}"
+parse "" "" <<< "${INPUT}"
+