Qore FixedLengthUtil Module Reference  1.0
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FixedLengthUtil::FixedLengthFileIterator Class Reference

Structured line iterator for fixed-length line files allowing efficient "pipelined" processing. More...

Inheritance diagram for FixedLengthUtil::FixedLengthFileIterator:

Public Member Functions

 constructor (string file_name, hash spec, *hash opts)
 Instantiates the FixedLengthFileIterator object. More...
 
private string getLine ()
 returns a line
 
bool next ()
 Moves the current line / record position to the next line / record; returns False if there are no more lines to iterate. More...
 
- Public Member Functions inherited from FixedLengthUtil::FixedLengthAbstractIterator
private *hash checkOptions (*hash opts)
 Validate and prepare global fixed-length options. More...
 
bool checkTransition (*string from, *string to)
 A verification function to be called for each line. This method can be overridden to achieve a begin-to-end validation of the whole input file. More...
 
 constructor (hash spec, *hash opts)
 Instantiates the FixedLengthAbstractIterator object. More...
 
*hash getValue ()
 Returns the current record as a hash. More...
 
string identifyType (string input_line)
 Identify a fixed-length line type using identifyTypeImpl(), that may be overridden if necessary. More...
 
*string identifyTypeImpl (string input_line)
 Identify a fixed-length line type, given the raw line string. This method performs a lookup to a precalculated table based on line lengths (see constructor()). In case different criteria are needed, eg. when two line types in a spec have the same length and no unique resolving rule are specified, this method needs to be overridden, and will throw an exception, because the precalculated mapping will be empty. More...
 
any transform (any value, hash type)
 parses the input value based on global configuration and the current field definition
 

Detailed Description

Structured line iterator for fixed-length line files allowing efficient "pipelined" processing.

Example:
1 #!/usr/bin/env qore
2 
3 %new-style
4 %enable-all-warnings
5 %require-types
6 %strict-args
7 
8 %requires FixedLengthUtil
9 
10 hash specs = (
11  "type1" : (
12  "col1": ("length": 5, "type": "int"),
13  "col2": ("length": 2, "type": "string"),
14  ),
15  "type2" : (
16  "col3": ("length": 1, "type": "string"),
17  "col4": ("length": 3, "type": "string"),
18  "col5": ("length": 8, "type": "date", "format": "DDMMYYYY",
19  #"timezone": "Europe/Prague", # use global if omitted
20  ),
21  ),
22 );
23 
24 hash global_options = (
25  "encoding" : "UTF-8",
26  "eol" : "\n",
27  "ignore_empty" : True,
28  "timezone" : "Europe/Prague", # used if not overridden in a date field specification
29 );
30 
31 FixedLengthFileIterator i(file, specs, global_options);
32 # output all records
33 map printf("%y\n", $1), i;

Member Function Documentation

FixedLengthUtil::FixedLengthFileIterator::constructor ( string  file_name,
hash  spec,
*hash  opts 
)

Instantiates the FixedLengthFileIterator object.

Parameters
file_nameFile path to read
specFixed-length line specification; see Specification Hash for more information
optsGlobal options; see Global Options for more information
bool FixedLengthUtil::FixedLengthFileIterator::next ( )

Moves the current line / record position to the next line / record; returns False if there are no more lines to iterate.

This method will return True again after it returns False once if the file being iterated has data that can be iterated, otherwise it will always return False. The iterator object should not be used to retrieve a value after this method returns False.

Returns
False if there are no lines / records to iterate (in which case the iterator object is invalid and should not be used); True if successful (meaning that the iterator object is valid)
Note
that empty lines are ignored if "ignore_empty" option is in effect