#!/usr/bin/perl
use 5.024;
use JSON::XS;
use strict;
use warnings;

#################
# CHUNK_LENGTH is intentionally tiny to highlight the error
my $CHUNK_LENGTH = \1;
#################

###################
## MAIN
{
  my $json = new JSON::XS;
  my $buffer;
  my $statement_count = 0;
  
  # Incrementally parse an array of JSON objects
  local $/ = $CHUNK_LENGTH;
  
  # first parse the initial "["
  INITIAL_PARSE_LOOP: while ( 1 ) {
    $buffer = <DATA>;
    $json->incr_parse($buffer); # void context, so no parsing
    
    # Exit the loop once we found the initial "[".
    # In essence, we are (ab-)using the $json object as a simple scala
+r
    # we append data to.
    last INITIAL_PARSE_LOOP if $json->incr_text =~ s/^.*?\[//msx;
  }
  
  # now we have the skipped the initial "[", so continue
  # parsing all the elements.
  PARSE_LOOP: while ( 1 ) {
    # clean up whitespace and padding
    $json->incr_text =~ s/^\s*(.+)\n/$1/gms;
    
    # in this loop we read data until we got a single JSON object
    STATEMENT_PARSE_LOOP: while ( 1 ) {
      if ( my $obj = $json->incr_parse ) {
        say "End of document ".++$statement_count;
        
        last STATEMENT_PARSE_LOOP;
      }
      
      # add more data
      $buffer = <DATA>;
      $json->incr_parse($buffer); # void context, so no parsing
    }
    
    # in this loop we read data until we either found and parsed the
    # separating "," between elements, or the final "]"
    CLEAN_UP_LOOP: while ( 1 ) {
      # first skip whitespace
      $json->incr_text =~ s/^\s*//;
      
      # if we find "]", we are done with the file
      last PARSE_LOOP if $json->incr_text =~ s/^\]//;
      
      # if we find ",", we can continue with the next element
      last CLEAN_UP_LOOP if $json->incr_text =~ s/^,//;
      
      # if we find anything else, we have a parse error!
      if ( length $json->incr_text ) {
        die "parse error near ".$json->incr_text;
      }
      
      # else add more data
      $buffer = <DATA>;
      $json->incr_parse($buffer); # void context, so no parsing
    }
  }
}

__DATA__
[
{
  "name": "xxxxxxxxxxxxxxx",
  "id": "xxxxxxxxxxxxxx",
  "previousBalance": "xxxxx",
  "currentMonth": "xxxxxxx",
  "total": "xxxxxxxx",
  "billingDate": "xxxxxxxxxxxxxx",
  "billingPeriod": "xxxxxxxxxxxxxxxxxxxxxxx",
  "invoiceDate": "xxxxxxxxxxx",
  "dueDate": "xxxxxxxxxxx",
  "autopay": false,
  "address": {
    "line1": "xxxxxxxxxxxxx",
    "line2": null,
    "city": "xxxxxxxxxxxx",
    "state": "xx",
    "zip": "xxxxxxxxxxx"
  }
},
{
  "name": "xxxxxxxxxxxxxxx",
  "id": "xxxxxxxxxxxxxx",
  "previousBalance": "xxxxx",
  "currentMonth": "xxxxxxx",
  "total": "xxxxxxxx",
  "billingDate": "xxxxxxxxxxxxxx",
  "billingPeriod": "xxxxxxxxxxxxxxxxxxxxxxx",
  "invoiceDate": "xxxxxxxxxxx",
  "dueDate": "xxxxxxxxxxx",
  "autopay": false,
  "address": {
    "line1": "xxxxxxxxxxxxx",
    "line2": null,
    "city": "xxxxxxxxxxxx",
    "state": "xx",
    "zip": "xxxxxxxxxxx"
  }
}
]
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