bloblang

package
Version: v4.1.0 Latest Latest
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Published: May 11, 2022 License: MIT Imports: 10 Imported by: 1

Documentation

Overview

Package bloblang provides high level APIs for registering custom Bloblang plugins, as well as for parsing and executing Bloblang mappings.

For a video guide on Benthos plugins check out: https://youtu.be/uH6mKw-Ly0g And an example repo containing component plugins and tests can be found at: https://github.com/benthosdev/benthos-plugin-example

Plugins can either be registered globally, and will be accessible to any component parsing Bloblang expressions in the executable, or they can be registered as part of an isolated environment.

Example (BloblangFunctionPluginV1)

This example demonstrates how to create a Bloblang function with the simpler V1 API and execute them with a Bloblang mapping. Note that functions registered this way will NOT support named parameters, for named parameters use the V2 register API.

package main

import (
	"encoding/json"
	"fmt"

	"github.com/benthosdev/benthos/v4/public/bloblang"
)

func main() {
	if err := bloblang.RegisterFunction("add_but_always_slightly_wrong", func(args ...interface{}) (bloblang.Function, error) {
		var left, right float64

		if err := bloblang.NewArgSpec().
			Float64Var(&left).
			Float64Var(&right).
			Extract(args); err != nil {
			return nil, err
		}

		return func() (interface{}, error) {
			return left + right + 0.02, nil
		}, nil
	}); err != nil {
		panic(err)
	}

	mapping := `
root.num = add_but_always_slightly_wrong(this.a, this.b)
`

	exe, err := bloblang.Parse(mapping)
	if err != nil {
		panic(err)
	}

	res, err := exe.Query(map[string]interface{}{
		"a": 1.2, "b": 2.6,
	})
	if err != nil {
		panic(err)
	}

	jsonBytes, err := json.Marshal(res)
	if err != nil {
		panic(err)
	}

	fmt.Println(string(jsonBytes))
}
Output:

{"num":3.82}
Example (BloblangFunctionPluginV2)

This example demonstrates how to create Bloblang methods and functions and execute them with a Bloblang mapping using the new V2 methods, which adds support to our functions and methods for optional named parameters.

package main

import (
	"encoding/json"
	"fmt"

	"github.com/benthosdev/benthos/v4/public/bloblang"
)

func main() {
	multiplyWrongSpec := bloblang.NewPluginSpec().
		Description("Multiplies two numbers together but gets it slightly wrong. Whoops.").
		Param(bloblang.NewFloat64Param("left").Description("The first of two numbers to multiply.")).
		Param(bloblang.NewFloat64Param("right").Description("The second of two numbers to multiply."))

	if err := bloblang.RegisterFunctionV2(
		"multiply_but_always_slightly_wrong", multiplyWrongSpec,
		func(args *bloblang.ParsedParams) (bloblang.Function, error) {
			left, err := args.GetFloat64("left")
			if err != nil {
				return nil, err
			}

			right, err := args.GetFloat64("right")
			if err != nil {
				return nil, err
			}

			return func() (interface{}, error) {
				return left*right + 0.02, nil
			}, nil
		}); err != nil {
		panic(err)
	}

	// Our function now optionally supports named parameters, when a function is
	// instantiated with unamed parameters they must follow the order in which
	// the parameters are registered.
	mapping := `
root.num_ab = multiply_but_always_slightly_wrong(left: this.a, right: this.b)
root.num_cd = multiply_but_always_slightly_wrong(this.c, this.d)
`

	exe, err := bloblang.Parse(mapping)
	if err != nil {
		panic(err)
	}

	res, err := exe.Query(map[string]interface{}{
		"a": 1.2, "b": 2.6, "c": 5.3, "d": 8.2,
	})
	if err != nil {
		panic(err)
	}

	jsonBytes, err := json.Marshal(res)
	if err != nil {
		panic(err)
	}

	fmt.Println(string(jsonBytes))
}
Output:

{"num_ab":3.14,"num_cd":43.48}
Example (BloblangMethodPluginV1)

This example demonstrates how to create Bloblang methods with the simpler API and execute them with a Bloblang mapping. Note that methods registered this way will NOT support named parameters, for named parameters use the V2 register API.

package main

import (
	"encoding/json"
	"fmt"
	"math/rand"

	"github.com/benthosdev/benthos/v4/public/bloblang"
)

func main() {
	if err := bloblang.RegisterMethod("cuddle", func(args ...interface{}) (bloblang.Method, error) {
		var prefix string
		var suffix string

		if err := bloblang.NewArgSpec().
			StringVar(&prefix).
			StringVar(&suffix).
			Extract(args); err != nil {
			return nil, err
		}

		return bloblang.StringMethod(func(s string) (interface{}, error) {
			return prefix + s + suffix, nil
		}), nil
	}); err != nil {
		panic(err)
	}

	if err := bloblang.RegisterMethod("shuffle", func(_ ...interface{}) (bloblang.Method, error) {
		rand := rand.New(rand.NewSource(0))
		return bloblang.ArrayMethod(func(in []interface{}) (interface{}, error) {
			out := make([]interface{}, len(in))
			copy(out, in)
			rand.Shuffle(len(out), func(i, j int) {
				out[i], out[j] = out[j], out[i]
			})
			return out, nil
		}), nil
	}); err != nil {
		panic(err)
	}

	mapping := `
root.new_summary = this.summary.cuddle("meow", "woof")
root.shuffled = this.names.shuffle()
`

	exe, err := bloblang.Parse(mapping)
	if err != nil {
		panic(err)
	}

	res, err := exe.Query(map[string]interface{}{
		"summary": "quack",
		"names":   []interface{}{"denny", "pixie", "olaf", "jen", "spuz"},
	})
	if err != nil {
		panic(err)
	}

	jsonBytes, err := json.Marshal(res)
	if err != nil {
		panic(err)
	}

	fmt.Println(string(jsonBytes))
}
Output:

{"new_summary":"meowquackwoof","shuffled":["olaf","jen","pixie","denny","spuz"]}
Example (BloblangMethodPluginV2)

This example demonstrates how to create Bloblang methods and functions and execute them with a Bloblang mapping using the new V2 methods, which adds support to our functions and methods for optional named parameters.

package main

import (
	"encoding/json"
	"fmt"
	"math/rand"

	"github.com/benthosdev/benthos/v4/public/bloblang"
)

func main() {
	hugStringSpec := bloblang.NewPluginSpec().
		Description("Wraps a string with a prefix and suffix.").
		Param(bloblang.NewStringParam("prefix").Description("The prefix to insert.")).
		Param(bloblang.NewStringParam("suffix").Description("The suffix to append."))

	if err := bloblang.RegisterMethodV2("hug_string", hugStringSpec, func(args *bloblang.ParsedParams) (bloblang.Method, error) {
		prefix, err := args.GetString("prefix")
		if err != nil {
			return nil, err
		}

		suffix, err := args.GetString("suffix")
		if err != nil {
			return nil, err
		}

		return bloblang.StringMethod(func(s string) (interface{}, error) {
			return prefix + s + suffix, nil
		}), nil
	}); err != nil {
		panic(err)
	}

	reverseSpec := bloblang.NewPluginSpec().
		Description("Reverses the order of an array target, but sometimes it randomly doesn't. Whoops.")

	if err := bloblang.RegisterMethodV2("sometimes_reverse", reverseSpec, func(*bloblang.ParsedParams) (bloblang.Method, error) {
		rand := rand.New(rand.NewSource(0))
		return bloblang.ArrayMethod(func(in []interface{}) (interface{}, error) {
			if rand.Int()%3 == 0 {
				// Whoopsie
				return in, nil
			}
			out := make([]interface{}, len(in))
			copy(out, in)
			for i, j := 0, len(out)-1; i < j; i, j = i+1, j-1 {
				out[i], out[j] = out[j], out[i]
			}
			return out, nil
		}), nil
	}); err != nil {
		panic(err)
	}

	// Our methods now optionally support named parameters, when a method is
	// instantiated with unamed parameters they must follow the order in which
	// the parameters are registered.
	mapping := `
root.new_summary = this.summary.hug_string(prefix: "meow", suffix: "woof")
root.reversed = this.names.sometimes_reverse()
`

	exe, err := bloblang.Parse(mapping)
	if err != nil {
		panic(err)
	}

	res, err := exe.Query(map[string]interface{}{
		"summary": "quack",
		"names":   []interface{}{"denny", "pixie", "olaf", "jen", "spuz"},
	})
	if err != nil {
		panic(err)
	}

	jsonBytes, err := json.Marshal(res)
	if err != nil {
		panic(err)
	}

	fmt.Println(string(jsonBytes))
}
Output:

{"new_summary":"meowquackwoof","reversed":["spuz","jen","olaf","pixie","denny"]}
Example (BloblangRestrictedEnvironment)

This example demonstrates how to create and use an isolated Bloblang environment with some standard functions removed.

package main

import (
	"encoding/json"
	"fmt"
	"strings"

	"github.com/benthosdev/benthos/v4/public/bloblang"
)

func main() {
	env := bloblang.NewEnvironment().WithoutFunctions("env", "file")

	if err := env.RegisterMethod("custom_thing", func(args ...interface{}) (bloblang.Method, error) {
		return bloblang.StringMethod(func(s string) (interface{}, error) {
			return strings.ToUpper(s), nil
		}), nil
	}); err != nil {
		panic(err)
	}

	mapping := `
root.foo = this.foo.string()
root.bar = this.bar + this.baz
root.buz = this.buz.content.custom_thing()
`

	exe, err := env.Parse(mapping)
	if err != nil {
		panic(err)
	}

	res, err := exe.Query(map[string]interface{}{
		"foo": 50.0,
		"bar": "first bit ",
		"baz": "second bit",
		"buz": map[string]interface{}{
			"id":      "XXXX",
			"content": "some nested content",
		},
	})
	if err != nil {
		panic(err)
	}

	jsonBytes, err := json.Marshal(res)
	if err != nil {
		panic(err)
	}

	fmt.Println(string(jsonBytes))
}
Output:

{"bar":"first bit second bit","buz":"SOME NESTED CONTENT","foo":"50"}

Index

Examples

Constants

This section is empty.

Variables

View Source
var ErrRootDeleted = errors.New("root was deleted")

ErrRootDeleted is returned by a Bloblang query when the mapping results in the root being deleted. It might be considered correct to do this in situations where filtering is allowed or expected.

Functions

func RegisterFunction

func RegisterFunction(name string, ctor FunctionConstructor) error

RegisterFunction adds a new Bloblang function to the global environment. All function names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func RegisterFunctionV2

func RegisterFunctionV2(name string, spec *PluginSpec, ctor FunctionConstructorV2) error

RegisterFunctionV2 adds a new Bloblang function to the global environment. All function names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func RegisterMethod

func RegisterMethod(name string, ctor MethodConstructor) error

RegisterMethod adds a new Bloblang method to the global environment. All method names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func RegisterMethodV2

func RegisterMethodV2(name string, spec *PluginSpec, ctor MethodConstructorV2) error

RegisterMethodV2 adds a new Bloblang method to the global environment. All method names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

Types

type ArgError

type ArgError struct {
	// The argument index
	Index int

	// The expected argument type
	ExpectedKind reflect.Kind

	// The actual type provided
	ActualKind reflect.Kind

	// The value of the argument
	Value interface{}
}

ArgError represents an error encountered when parsing a function or method argument.

func (*ArgError) Error

func (a *ArgError) Error() string

type ArgSpec

type ArgSpec struct {
	// contains filtered or unexported fields
}

ArgSpec provides an API for validating and extracting function or method arguments by registering them with pointer receivers.

func NewArgSpec

func NewArgSpec() *ArgSpec

NewArgSpec creates an argument parser/validator.

func (*ArgSpec) AnyVar

func (a *ArgSpec) AnyVar(i *interface{}) *ArgSpec

AnyVar creates an argument to follow the previously created argument that can have any value.

func (*ArgSpec) BoolVar

func (a *ArgSpec) BoolVar(b *bool) *ArgSpec

BoolVar creates a boolean argument to follow the previously created argument.

func (*ArgSpec) Extract

func (a *ArgSpec) Extract(args []interface{}) error

Extract the specified typed arguments from a slice of generic arguments. Returns an error if the number of arguments does not match the spec, and returns an *ArgError if the type of an argument is mismatched.

func (*ArgSpec) Float64Var

func (a *ArgSpec) Float64Var(f *float64) *ArgSpec

Float64Var creates a Float64 argument to follow the previously created argument.

func (*ArgSpec) Int64Var

func (a *ArgSpec) Int64Var(i *int64) *ArgSpec

Int64Var creates an int64 argument to follow the previously created argument.

func (*ArgSpec) IntVar

func (a *ArgSpec) IntVar(i *int) *ArgSpec

IntVar creates an int argument to follow the previously created argument.

func (*ArgSpec) StringVar

func (a *ArgSpec) StringVar(s *string) *ArgSpec

StringVar creates a string argument to follow the previously created argument.

type Environment

type Environment struct {
	// contains filtered or unexported fields
}

Environment provides an isolated Bloblang environment where the available features, functions and methods can be modified.

func GlobalEnvironment

func GlobalEnvironment() *Environment

GlobalEnvironment returns the global default environment. Modifying this environment will impact all Bloblang parses that aren't initialized with an isolated environment, as well as any new environments initialized after the changes.

func NewEmptyEnvironment

func NewEmptyEnvironment() *Environment

NewEmptyEnvironment creates a fresh Bloblang environment starting completely empty, where no functions or methods are initially available.

func NewEnvironment

func NewEnvironment() *Environment

NewEnvironment creates a fresh Bloblang environment, starting with the full range of globally defined features (functions and methods), and provides APIs for expanding or contracting the features available to this environment.

It's worth using an environment when you need to restrict the access or capabilities that certain bloblang mappings have versus others.

For example, an environment could be created that removes any functions for accessing environment variables or reading data from the host disk, which could be used in certain situations without removing those functions globally for all mappings.

func XWrapEnvironment

func XWrapEnvironment(v interface{}) *Environment

XWrapEnvironment is for internal use only, do not use this.

func (*Environment) Clone

func (e *Environment) Clone() *Environment

Clone an environment in order to register functions and methods without modifying the existing environment.

func (*Environment) Deactivated

func (e *Environment) Deactivated() *Environment

Deactivated returns a version of the environment where constructors are disabled for all functions and methods, allowing mappings to be parsed and validated but not executed.

The underlying register of functions and methods is shared with the target environment, and therefore functions/methods registered to this set will also be added to the still activated environment. Use Clone in order to avoid this.

func (*Environment) OnlyPure

func (e *Environment) OnlyPure() *Environment

OnlyPure removes any methods and functions that have been registered but are marked as impure. Impure in this context means the method/function is able to mutate global state or access machine state (read environment variables, files, etc). Note that methods/functions that access the machine clock are not marked as pure, so timestamp functions will still work.

func (*Environment) Parse

func (e *Environment) Parse(blobl string) (*Executor, error)

Parse a Bloblang mapping using the Environment to determine the features (functions and methods) available to the mapping.

When a parsing error occurs the error will be the type *ParseError, which gives access to the line and column where the error occurred, as well as a method for creating a well formatted error message.

func (*Environment) RegisterFunction

func (e *Environment) RegisterFunction(name string, ctor FunctionConstructor) error

RegisterFunction adds a new Bloblang function to the environment. All function names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func (*Environment) RegisterFunctionV2

func (e *Environment) RegisterFunctionV2(name string, spec *PluginSpec, ctor FunctionConstructorV2) error

RegisterFunctionV2 adds a new Bloblang function to the environment using a provided ParamsSpec to define the name of the function and its parameters.

Plugin names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func (*Environment) RegisterMethod

func (e *Environment) RegisterMethod(name string, ctor MethodConstructor) error

RegisterMethod adds a new Bloblang method to the environment. All method names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func (*Environment) RegisterMethodV2

func (e *Environment) RegisterMethodV2(name string, spec *PluginSpec, ctor MethodConstructorV2) error

RegisterMethodV2 adds a new Bloblang method to the environment using a provided ParamsSpec to define the name of the method and its parameters.

Plugin names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func (*Environment) WalkFunctions

func (e *Environment) WalkFunctions(fn func(name string, spec *FunctionView))

WalkFunctions executes a provided function argument for every function that has been registered to the environment.

func (*Environment) WalkMethods

func (e *Environment) WalkMethods(fn func(name string, spec *MethodView))

WalkMethods executes a provided function argument for every method that has been registered to the environment.

func (*Environment) WithCustomImporter

func (e *Environment) WithCustomImporter(fn func(name string) ([]byte, error)) *Environment

WithCustomImporter returns a copy of the environment where imports from mappings are done via a provided closure function.

func (*Environment) WithDisabledImports

func (e *Environment) WithDisabledImports() *Environment

WithDisabledImports returns a copy of the environment where imports within mappings are disabled.

func (*Environment) WithMaxMapRecursion

func (e *Environment) WithMaxMapRecursion(n int) *Environment

WithMaxMapRecursion returns a copy of the environment where the maximum recursion allowed for maps is set to a given value. If the execution of a mapping from this environment matches this number of recursive map calls the mapping will error out.

func (*Environment) WithoutFunctions

func (e *Environment) WithoutFunctions(names ...string) *Environment

WithoutFunctions returns a copy of the environment but with a variadic list of function names removed. Instantiation of these removed functions within a mapping will cause errors at parse time.

func (*Environment) WithoutMethods

func (e *Environment) WithoutMethods(names ...string) *Environment

WithoutMethods returns a copy of the environment but with a variadic list of method names removed. Instantiation of these removed methods within a mapping will cause errors at parse time.

func (*Environment) XUnwrapper

func (e *Environment) XUnwrapper() interface{}

XUnwrapper is for internal use only, do not use this.

type Executor

type Executor struct {
	// contains filtered or unexported fields
}

Executor stores a parsed Bloblang mapping and provides APIs for executing it.

func Parse

func Parse(blobl string) (*Executor, error)

Parse a Bloblang mapping allowing the use of the globally accessible range of features (functions and methods).

When a parsing error occurs the error will be the type *ParseError, which gives access to the line and column where the error occurred, as well as a method for creating a well formatted error message.

func (*Executor) Overlay

func (e *Executor) Overlay(value interface{}, onto *interface{}) error

Overlay executes a Bloblang mapping against a value, where assignments are overlayed onto an existing structure.

If the mapping results in the root of the new document being deleted then ErrRootDeleted is returned, which can be used as a signal to filter rather than fail the mapping.

func (*Executor) Query

func (e *Executor) Query(value interface{}) (interface{}, error)

Query executes a Bloblang mapping against a value and returns the result. The argument and return values can be structured using the same map[string]interface{} and []interface{} types as would be returned by the Go standard json package unmarshaler.

If the mapping results in the root of the new document being deleted then ErrRootDeleted is returned, which can be used as a signal to filter rather than fail the mapping.

func (*Executor) XUnwrapper

func (e *Executor) XUnwrapper() interface{}

XUnwrapper is for internal use only, do not use this.

type Function

type Function func() (interface{}, error)

Function defines a Bloblang function, arguments are provided to the constructor, allowing the implementation of this function to resolve them statically when possible.

type FunctionConstructor

type FunctionConstructor func(args ...interface{}) (Function, error)

FunctionConstructor defines a constructor for a Bloblang function, where a variadic list of arguments are provided.

When a function is parsed from a mapping with static arguments the constructor will be called only once at parse time. When a function is parsed with dynamic arguments, such as a value derived from the mapping input, the constructor will be called on each invocation of the mapping with the derived arguments.

For a convenient way to perform type checking and coercion on the arguments use an ArgSpec.

type FunctionConstructorV2

type FunctionConstructorV2 func(args *ParsedParams) (Function, error)

FunctionConstructorV2 defines a constructor for a Bloblang function where parameters are parsed using a ParamsSpec provided when registering the function.

When a function is parsed from a mapping with static arguments the constructor will be called only once at parse time. When a function is parsed with dynamic arguments, such as a value derived from the mapping input, the constructor will be called on each invocation of the mapping with the derived arguments.

type FunctionView

type FunctionView struct {
	// contains filtered or unexported fields
}

FunctionView describes a particular function belonging to a Bloblang environment.

func (*FunctionView) Description

func (v *FunctionView) Description() string

Description provides an overview of the function.

func (*FunctionView) FormatJSON

func (v *FunctionView) FormatJSON() ([]byte, error)

FormatJSON returns a byte slice of the function configuration formatted as a JSON object. The schema of this method is undocumented and is not intended for general use.

Experimental: This method is not intended for general use and could have its signature and/or behaviour changed outside of major version bumps.

type Method

type Method func(v interface{}) (interface{}, error)

Method defines a Bloblang function that executes on a value. Arguments are provided to the constructor, allowing the implementation of this method to resolve them statically when possible.

In order to avoid type checking the value use one of the typed variants such as StringMethod.

func ArrayMethod

func ArrayMethod(methodFn func([]interface{}) (interface{}, error)) Method

ArrayMethod creates a general method signature from an array method by performing type checking on the method target.

func BoolMethod

func BoolMethod(methodFn func(bool) (interface{}, error)) Method

BoolMethod creates a general method signature from a bool method by performing type checking on the method target.

func BytesMethod

func BytesMethod(methodFn func([]byte) (interface{}, error)) Method

BytesMethod creates a general method signature from a byte slice method by performing type checking on the method target.

func Float64Method

func Float64Method(methodFn func(float64) (interface{}, error)) Method

Float64Method creates a general method signature from a float method by performing type checking on the method target.

func Int64Method

func Int64Method(methodFn func(int64) (interface{}, error)) Method

Int64Method creates a general method signature from an int method by performing type checking on the method target.

func ObjectMethod

func ObjectMethod(methodFn func(obj map[string]interface{}) (interface{}, error)) Method

ObjectMethod creates a general method signature from an object method by performing type checking on the method target.

func StringMethod

func StringMethod(methodFn func(string) (interface{}, error)) Method

StringMethod creates a general method signature from a string method by performing type checking on the method target.

func TimestampMethod

func TimestampMethod(methodFn func(time.Time) (interface{}, error)) Method

TimestampMethod creates a general method signature from a timestamp method by performing type checking on the method target.

type MethodConstructor

type MethodConstructor func(args ...interface{}) (Method, error)

MethodConstructor defines a constructor for a Bloblang method, where a variadic list of arguments are provided.

When a method is parsed from a mapping with static arguments the constructor will be called only once at parse time. When a method is parsed with dynamic arguments, such as a value derived from the mapping input, the constructor will be called on each invocation of the mapping with the derived arguments.

For a convenient way to perform type checking and coercion on the arguments use an ArgSpec.

type MethodConstructorV2

type MethodConstructorV2 func(args *ParsedParams) (Method, error)

MethodConstructorV2 defines a constructor for a Bloblang method where parameters are parsed using a ParamsSpec provided when registering the method.

When a method is parsed from a mapping with static arguments the constructor will be called only once at parse time. When a method is parsed with dynamic arguments, such as a value derived from the mapping input, the constructor will be called on each invocation of the mapping with the derived arguments.

type MethodView

type MethodView struct {
	// contains filtered or unexported fields
}

MethodView describes a particular method belonging to a Bloblang environment.

func (*MethodView) Description

func (v *MethodView) Description() string

Description provides an overview of the method.

func (*MethodView) FormatJSON

func (v *MethodView) FormatJSON() ([]byte, error)

FormatJSON returns a byte slice of the method configuration formatted as a JSON object. The schema of this method is undocumented and is not intended for general use.

Experimental: This method is not intended for general use and could have its signature and/or behaviour changed outside of major version bumps.

type ParamDefinition

type ParamDefinition struct {
	// contains filtered or unexported fields
}

ParamDefinition describes a single parameter for a function or method.

func NewAnyParam

func NewAnyParam(name string) ParamDefinition

NewAnyParam creates a new parameter that can be any type. Parameter names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func NewBoolParam

func NewBoolParam(name string) ParamDefinition

NewBoolParam creates a new bool typed parameter. Parameter names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func NewFloat64Param

func NewFloat64Param(name string) ParamDefinition

NewFloat64Param creates a new float64 typed parameter. Parameter names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func NewInt64Param

func NewInt64Param(name string) ParamDefinition

NewInt64Param creates a new 64-bit integer typed parameter. Parameter names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func NewStringParam

func NewStringParam(name string) ParamDefinition

NewStringParam creates a new string typed parameter. Parameter names must match the regular expression /^[a-z0-9]+(_[a-z0-9]+)*$/ (snake case).

func (ParamDefinition) Default

func (d ParamDefinition) Default(v interface{}) ParamDefinition

Default adds a default value to a parameter, also making it implicitly optional.

func (ParamDefinition) Description

func (d ParamDefinition) Description(str string) ParamDefinition

Description adds an optional description to the parameter definition, this is used when generating documentation for the parameter to describe what the parameter is for.

func (ParamDefinition) Optional

func (d ParamDefinition) Optional() ParamDefinition

Optional marks the parameter as optional.

type ParseError

type ParseError struct {
	Line   int
	Column int
	// contains filtered or unexported fields
}

ParseError is a structured error type for Bloblang parser errors that provides access to information such as the line and column where the error occurred.

func (*ParseError) Error

func (p *ParseError) Error() string

Error returns a single line error string.

func (*ParseError) ErrorMultiline

func (p *ParseError) ErrorMultiline() string

ErrorMultiline returns an error string spanning multiple lines that provides a cleaner view of the specific error.

type ParsedParams

type ParsedParams struct {
	// contains filtered or unexported fields
}

ParsedParams is a reference to the arguments of a method or function instantiation.

func (*ParsedParams) Get

func (p *ParsedParams) Get(name string) (interface{}, error)

Get an argument value with a given name and return it boxed within an empty interface.

func (*ParsedParams) GetBool

func (p *ParsedParams) GetBool(name string) (bool, error)

GetBool returns a bool argument value with a given name.

func (*ParsedParams) GetFloat64

func (p *ParsedParams) GetFloat64(name string) (float64, error)

GetFloat64 returns a float argument value with a given name.

func (*ParsedParams) GetInt64

func (p *ParsedParams) GetInt64(name string) (int64, error)

GetInt64 returns an integer argument value with a given name.

func (*ParsedParams) GetOptionalBool

func (p *ParsedParams) GetOptionalBool(name string) (*bool, error)

GetOptionalBool returns a bool argument value with a given name if it was defined, otherwise nil.

func (*ParsedParams) GetOptionalFloat64

func (p *ParsedParams) GetOptionalFloat64(name string) (*float64, error)

GetOptionalFloat64 returns a float argument value with a given name if it was defined, otherwise nil.

func (*ParsedParams) GetOptionalInt64

func (p *ParsedParams) GetOptionalInt64(name string) (*int64, error)

GetOptionalInt64 returns an int argument value with a given name if it was defined, otherwise nil.

func (*ParsedParams) GetOptionalString

func (p *ParsedParams) GetOptionalString(name string) (*string, error)

GetOptionalString returns a string argument value with a given name if it was defined, otherwise nil.

func (*ParsedParams) GetString

func (p *ParsedParams) GetString(name string) (string, error)

GetString returns a string argument value with a given name.

type PluginSpec

type PluginSpec struct {
	// contains filtered or unexported fields
}

PluginSpec documents and defines the parameters of a function or method and the way in which it should be used.

Using a plugin spec with explicit parameters means that instantiations of the plugin can be done using either classic argument types (foo, bar, baz), following the order in which the parameters are added, or named style (c: baz, a: foo).

func NewPluginSpec

func NewPluginSpec() *PluginSpec

NewPluginSpec creates a new plugin definition for a function or method plugin that describes the arguments that the plugin expects.

func (*PluginSpec) Category

func (p *PluginSpec) Category(str string) *PluginSpec

Category adds an optional category string to the plugin spec, this is used when generating documentation for the plugin.

func (*PluginSpec) Description

func (p *PluginSpec) Description(str string) *PluginSpec

Description adds an optional description to the plugin spec, this is used when generating documentation for the plugin.

func (*PluginSpec) EncodeJSON

func (p *PluginSpec) EncodeJSON(v []byte) error

EncodeJSON attempts to parse a JSON object as a byte slice and uses it to populate the configuration spec. The schema of this method is undocumented and is not intended for general use.

Experimental: This method is not intended for general use and could have its signature and/or behaviour changed outside of major version bumps.

func (*PluginSpec) Example

func (p *PluginSpec) Example(summary, mapping string, inputOutputs ...[2]string) *PluginSpec

Example adds an optional example to the plugin spec, this is used when generating documentation for the plugin. An example consists of a short summary, a mapping demonstrating the plugin, and one or more input/output combinations.

func (*PluginSpec) Impure added in v4.1.0

func (p *PluginSpec) Impure() *PluginSpec

Impure marks the plugin as "impure", meaning it either reads from or interacts with state outside of the boundaries of a single mapping invocation. This usually means reading state from the machine. Impure plugins are excluded from some bloblang environments.

func (*PluginSpec) Param

func (p *PluginSpec) Param(def ParamDefinition) *PluginSpec

Param adds a parameter to the spec. Instantiations of the plugin with nameless arguments (foo, bar, baz) must follow the order in which fields are added to the spec.

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