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#
# JSON parser for Tcl.
#
# See http://www.json.org/ && http://www.ietf.org/rfc/rfc4627.txt
#
# Total rework of the code published with version number 1.0 by
# Thomas Maeder, Glue Software Engineering AG
#
# $Id: json.tcl,v 1.7 2011/11/10 21:05:58 andreas_kupries Exp $
#
if {![package vsatisfies [package provide Tcl] 8.5]} {
package require dict
}
# Parse JSON text into a dict
# @param jsonText JSON text
# @return dict (or list) containing the object represented by $jsonText
proc ::json::json2dict_tcl {jsonText} {
variable tokenRE
set tokens [regexp -all -inline -- $tokenRE $jsonText]
set nrTokens [llength $tokens]
set tokenCursor 0
#puts I:($jsonText)
#puts T:\t[join $tokens \nT:\t]
return [parseValue $tokens $nrTokens tokenCursor]
}
# Parse multiple JSON entities in a string into a list of dictionaries
# @param jsonText JSON text to parse
# @param max Max number of entities to extract.
# @return list of (dict (or list) containing the objects) represented by $jsonText
proc ::json::many-json2dict_tcl {jsonText {max -1}} {
variable tokenRE
if {$max == 0} {
return -code error -errorCode {JSON BAD-LIMIT ZERO} \
"Bad limit 0 of json entities to extract."
}
set tokens [regexp -all -inline -- $tokenRE $jsonText]
set nrTokens [llength $tokens]
set tokenCursor 0
set result {}
set found 0
set n $max
while {$n != 0} {
if {$tokenCursor >= $nrTokens} break
lappend result [parseValue $tokens $nrTokens tokenCursor]
incr found
if {$n > 0} {incr n -1}
}
if {$n > 0} {
return -code error -errorCode {JSON BAD-LIMIT TOO LARGE} \
"Bad limit $max of json entities to extract, found only $found."
}
return $result
}
# Throw an exception signaling an unexpected token
proc ::json::unexpected {tokenCursor token expected} {
return -code error -errorcode [list JSON UNEXPECTED $tokenCursor $expected] \
"unexpected token \"$token\" at position $tokenCursor; expecting $expected"
}
# Get rid of the quotes surrounding a string token and substitute the
# real characters for escape sequences within it
# @param token
# @return unquoted unescaped value of the string contained in $token
proc ::json::unquoteUnescapeString {tokenCursor token} {
variable stringREv
set unquoted [string range $token 1 end-1]
if {![regexp $stringREv $token]} {
unexpected $tokenCursor $token STRING
}
set res [subst -nocommands -novariables $unquoted]
return $res
}
# Parse an object member
# @param tokens list of tokens
# @param nrTokens length of $tokens
# @param tokenCursorName name (in caller's context) of variable
# holding current position in $tokens
# @param objectDictName name (in caller's context) of dict
# representing the JSON object of which to
# parse the next member
proc ::json::parseObjectMember {tokens nrTokens tokenCursorName objectDictName} {
upvar $tokenCursorName tokenCursor
upvar $objectDictName objectDict
set token [lindex $tokens $tokenCursor]
set tc $tokenCursor
incr tokenCursor
set leadingChar [string index $token 0]
if {$leadingChar eq "\""} {
set memberName [unquoteUnescapeString $tc $token]
if {$tokenCursor == $nrTokens} {
unexpected $tokenCursor "END" "\":\""
} else {
set token [lindex $tokens $tokenCursor]
incr tokenCursor
if {$token eq ":"} {
set memberValue [parseValue $tokens $nrTokens tokenCursor]
dict set objectDict $memberName $memberValue
} else {
unexpected $tokenCursor $token "\":\""
}
}
} else {
unexpected $tokenCursor $token "STRING"
}
}
# Parse the members of an object
# @param tokens list of tokens
# @param nrTokens length of $tokens
# @param tokenCursorName name (in caller's context) of variable
# holding current position in $tokens
# @param objectDictName name (in caller's context) of dict
# representing the JSON object of which to
# parse the next member
proc ::json::parseObjectMembers {tokens nrTokens tokenCursorName objectDictName} {
upvar $tokenCursorName tokenCursor
upvar $objectDictName objectDict
while true {
parseObjectMember $tokens $nrTokens tokenCursor objectDict
set token [lindex $tokens $tokenCursor]
incr tokenCursor
switch -exact $token {
"," {
# continue
}
"\}" {
break
}
default {
unexpected $tokenCursor $token "\",\"|\"\}\""
}
}
}
}
# Parse an object
# @param tokens list of tokens
# @param nrTokens length of $tokens
# @param tokenCursorName name (in caller's context) of variable
# holding current position in $tokens
# @return parsed object (Tcl dict)
proc ::json::parseObject {tokens nrTokens tokenCursorName} {
upvar $tokenCursorName tokenCursor
if {$tokenCursor == $nrTokens} {
unexpected $tokenCursor "END" "OBJECT"
} else {
set result [dict create]
set token [lindex $tokens $tokenCursor]
if {$token eq "\}"} {
# empty object
incr tokenCursor
} else {
parseObjectMembers $tokens $nrTokens tokenCursor result
}
return $result
}
}
# Parse the elements of an array
# @param tokens list of tokens
# @param nrTokens length of $tokens
# @param tokenCursorName name (in caller's context) of variable
# holding current position in $tokens
# @param resultName name (in caller's context) of the list
# representing the JSON array
proc ::json::parseArrayElements {tokens nrTokens tokenCursorName resultName} {
upvar $tokenCursorName tokenCursor
upvar $resultName result
while true {
lappend result [parseValue $tokens $nrTokens tokenCursor]
if {$tokenCursor == $nrTokens} {
unexpected $tokenCursor "END" "\",\"|\"\]\""
} else {
set token [lindex $tokens $tokenCursor]
incr tokenCursor
switch -exact $token {
"," {
# continue
}
"\]" {
break
}
default {
unexpected $tokenCursor $token "\",\"|\"\]\""
}
}
}
}
}
# Parse an array
# @param tokens list of tokens
# @param nrTokens length of $tokens
# @param tokenCursorName name (in caller's context) of variable
# holding current position in $tokens
# @return parsed array (Tcl list)
proc ::json::parseArray {tokens nrTokens tokenCursorName} {
upvar $tokenCursorName tokenCursor
if {$tokenCursor == $nrTokens} {
unexpected $tokenCursor "END" "ARRAY"
} else {
set result {}
set token [lindex $tokens $tokenCursor]
set leadingChar [string index $token 0]
if {$leadingChar eq "\]"} {
# empty array
incr tokenCursor
} else {
parseArrayElements $tokens $nrTokens tokenCursor result
}
return $result
}
}
# Parse a value
# @param tokens list of tokens
# @param nrTokens length of $tokens
# @param tokenCursorName name (in caller's context) of variable
# holding current position in $tokens
# @return parsed value (dict, list, string, number)
proc ::json::parseValue {tokens nrTokens tokenCursorName} {
upvar $tokenCursorName tokenCursor
if {$tokenCursor == $nrTokens} {
unexpected $tokenCursor "END" "VALUE"
} else {
set token [lindex $tokens $tokenCursor]
set tc $tokenCursor
incr tokenCursor
set leadingChar [string index $token 0]
switch -exact -- $leadingChar {
"\{" {
return [parseObject $tokens $nrTokens tokenCursor]
}
"\[" {
return [parseArray $tokens $nrTokens tokenCursor]
}
"\"" {
# quoted string
return [unquoteUnescapeString $tc $token]
}
"t" -
"f" -
"n" {
# bare word: true, false, null (return as is)
return $token
}
default {
# number?
if {[string is double -strict $token]} {
return $token
} else {
unexpected $tokenCursor $token "VALUE"
}
}
}
}
}
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