Squirro Script Reference

This is the language reference for the Squirro Script language.

The syntax of Squirro Script strongly resembled Python, but the complexity and functionality has been reduced. On the other hand Squirro Script is optimised for dealing with Squirro items, especially around how functions are used on keywords and the functions that are provided. For cases where Squirro Script is not powerful enough, pipelets can be used to use the full power of Python instead.

Table of Contents

Language Primer

Squirro Script is modelled very closely after Python with only small syntax additions. Note however, that compared to Python only very limited functionality is available.

Example

An example script could look like this:

hours = minutes / 60

if len($title) > 40:
    $title = trim(substr($title, 0, 40)) + '…'

This simple script calculates the hours keyword from the minutes keyword. It then shortens the title to a most 40 characters with an ellipsis.

Variables

There are three types of variables available. The Item Format documentation contains full details on the possible fields and keywords available.

Variable can be assigned with the = operator

Data types

There are four types of variables:

• string
• int
• float
• datetime

The types correspond to the type of Squirro facets The type of a variable is implicitly defined by the assigned value, or explicitly by using one of the to_* functions.

Literals (values)

Squirro Script supports strings and numbers. Strings are always assumed to be Unicode and are assumed to be UTF-8 encoded. Numbers can be full numbers (int) or contain a decimal separator (float). Examples: 42 or 3.1415926).

Conditions

Conditional logic can be implemented with the if block. Example:

if @tlen > 40:
    $title = $title + '…'
    short_title = 'false'
elif @tlen == 0:
    $title = "No title"
    short_title = 'true'
else:
    short_title = 'true'

Each if block has an indented block of code to be executed when the comparison returns true. Any number of optional elif blocks can be added which are executed if the respective condition matches. Optionally an else block can be used at the end for when none of the comparisons matches.

For comparison the operators == (equal), != (not equal), '>' (greater than), '>=' (greater or equal), '<' (less than) and '<=' (less or equal) are available. If no comparison operator is used (such as if $title:), then the variable is treated as true if it is non-empty and not zero.

Operators

Operators can be used anywhere a variable can be referenced. The two sides of the operator can be any function call or variable. For example:

@offset = len($title) - 10

The following operators are provided:

• +: for addition or concatenation.
• -: for subtraction of numeric values.

• *: for multiplication of two numeric values.
• /: for division of numeric values.

Lookup Tables

Lookup tables are used to link data in processed Squirro items to some other database. For this purpose lookup tables are provided in Squirro Script. When you need more matching capabilities, Known Entity Extraction is another way to go.

A lookup table is instantiated with a load_table_ function, such as load_table_from_json. Values can then be looked up using the lookup function, which will return a record based on the passed in key. Finally the extend_keywords function is a helper to be able to work with more complex return values. It takes a table return value and assigns each value to the item keywords.

This whole process is best illustrated with an example.

Take the following input file (the lookup table) and Squirro item:

{
    "iphone": {
        "category": "phone",
        "vendor": "Apple Inc."
    },
    "firefox": {
        "category": ["browser", "software"],
        "vendor": "Mozilla"
    }
}

{
    "title": "Example",
    "keywords": {
        "products": ["firefox"]
    }
}

The following Squirro script will take the products keyword and look it up in the lookup table:

# Reads information from a product database (stored in JSON).
@product_table = load_table_from_json('products.json')
@products = lookup(@product_table, products)
extend_keywords(@products)

This will result in the following output item:

{
    "title": "Example",
    "keywords": {
        "products": ["firefox"],
        "category": ["browser", "software"],
        "vendor": ["Mozilla"]
    }
}

Functions

Functions can be called anywhere a variable can be referenced. For example:

title_hash = sha1($title)
if len($title) > 40:
    $title += '…'

When called on a keyword, then most functions are called on each individual value. The notable exception are the aggregation functions, which work on the entire list.

The following example shows the difference between a normal function (len) and an aggregation function (count).

attendee_count = count(attendees)
attendee_len = len(attendees)

{
  "title": "Example",
  "keywords": {
    "attendees": ["Jon", "Abigail", "Mark", "Rose ", "Isabella"]
  }
}

{
  "title": "Example",
  "keywords": {
    "attendees": ["Jon", "Abigail", "Mark", "Rose ", "Isabella"],
    "attendees_count": [5],
    "attendees_len": [3, 7, 4, 4, 8]
  }
}

String Functions

find(regexp[, field…])

Returns matches of the given regular expression in the input item and return any matching groups.

len(str)

Return the size of a string.

lower(str)

Returns a lower-cased version of the string.

sha1(str)

Return the SHA1 hash of the string.

sha256(str)

Return the SHA256 hash of the string.

sha512(str)

Return the SHA512 hash of the string.

strip(str)

Return a copy of the string with all whitespace removed at the beginning and end of the string.

substr(str, start, length)

Return a subset of the string, starting at start.

to_string(value)

Converts the given value to a string.

upper(str)

Returns a upper-cased version of the string.

xpath(expression)

Returns the text of the expressions matching the given XPath expression in the item body. An example which determines the title from the body:

@title = xpath("//h1")
if @title:
    $title = @title

xpath_clear(expression)

Removes all nodes that match the given XPath expression from the item body.

Numeric Functions

abs(num)

Returns the absolute value of the number.

round(number[, precision=0])

Rounds the number to the given precision. If precision is 0 (the default) an int number is returned. Otherwise a float with at most precision digits after the decimal point is returned.

to_float(value)

Converts the given value to a float.

to_int(value)

Converts the given value to an int.

Date Functions

datediff(date1, date2[, unit="seconds"])

Return the difference between the two given datetime objects. The unit can be specified as "seconds", "minutes", "hours", "days" or "weeks". Short versions of these units can be used, such as "s" for seconds.

to_datetime(value)

Converts the given value to a datetime. This only works if the string uses the Squirro datetime format (YYYY-MM-DDTHH:mm:ss).

Aggregation Functions

Aggregation functions are used on keywords and work on the entire list, instead of individual values. Most of the functions assume numeric values in the list.

avg(list_of_nums)

Return the average of all the values.

count(list)

Return the number of elements in the list.

max(list_of_nums)

Return the largest value of the list.

min(list_of_nums)

Return the smallest value of the list.

sum(list_of_nums)

Return the sum of all the values in the list.

Examples:

minutes_len = len(minutes)
minutes_count = count(minutes)
minutes_max = max(minutes)
minutes_min = min(minutes)
minutes_sum = sum(minutes)
minutes_avg = avg(minutes)

Lookup Table Functions

extend_keywords(key_value_dict)

Applies the return value from the lookup table to the item's keywords. The key_value_dict is a dictionary of key/value pairs, which is transformed into keywords on the items. The value can also be a list of such dictionaries, in which case each one is processed in turn.

load_table_from_json(filename)

Instantiates a lookup table by loading the given filename in JSON format. The format of the file is expected to be the following:

{
    "key": [
        {
            "output_key": "value",
            …
        },
        …
    ],
    …
}

lookup(table, keys)

Looks up the given key or keys in the lookup table. Returns a list of all the matching entries.

Other Functions

clear(variable)

Clears the given variable. This is usually used on facets or item fields to clear them.

discard()

Aborts execution of the script and discards the current item. This can be used to implement a stop criteria, where certain items shouldn't be indexed.

get_value(key)

Returns the value of the given variable. The key notation is the same as for any variables, with support for @ or $ prefix to access temporary variables or item fields.

The main use of this function is that it supports spaces in the keys. So this can be used to access keywords that contain spaces.

set_value(key, value)

Sets the value of the given variable. Like get_value, this method is mostly used to work with keywords that have spaces in their name.