miniohm

README

minohm-go

A Go implementation of the minohm interface, for using Ohm grammars from Go.

A grammar blob is an Ohm grammar that has been compiled to .wasm via the @ohm-js/wasm NPM package. To use a grammar blob to match some input, you need a miniohm implementation for your host language of choice (JavaScript, Go, Python, etc.) This package provides a miniohm implementation for the Go Programming Language.

Overview

The implementation consists of two main components:

1. matcher.go: A Go implementation of the JavaScript WasmMatcher class from the Ohm wasm package
2. testmain.go: A command-line program that demonstrates how to use the WasmMatcher

WasmMatcher

The WasmMatcher class provides a high-level API for working with Ohm grammar blobs:

matcher := NewWasmMatcher(ctx)
err := matcher.LoadModule("path/to/grammar.wasm")
matcher.SetInput("text to match")
success, err := matcher.Match()
success, err := matcher.MatchRule("specificRule")
cstRoot, err := matcher.GetCstRoot()

Walking the CST

A full implementation of semantics, operations, etc. is not part of the miniohm interface. Instead, you can walk the CST (concrete syntax tree) directly using the CstNode interface. See testmain.go for an example.

Developing

Useful commands:

make # Build
make test # Run tests

Documentation

Index

• Constants
• type CstNode
  • func NewCstNode(ruleNames []string, memory api.Memory, offset uint32) *CstNode
  • func (n *CstNode) Children() ([]*CstNode, error)
  • func (n *CstNode) IsIter() bool
  • func (n *CstNode) IsNonterminal() bool
  • func (n *CstNode) IsTerminal() bool
  • func (n *CstNode) MatchLength() (uint32, error)
  • func (n *CstNode) RuleName() (string, error)
  • func (n *CstNode) Type() int32
• type WasmMatcher
  • func NewWasmMatcher(ctx context.Context) *WasmMatcher
  • func (m *WasmMatcher) Close() error
  • func (m *WasmMatcher) GetCstRoot() (*CstNode, error)
  • func (m *WasmMatcher) GetInput() string
  • func (m *WasmMatcher) GetModule() api.Module
  • func (m *WasmMatcher) LoadModule(wasmPath string) error
  • func (m *WasmMatcher) Match(ruleName ...string) (bool, error)
  • func (m *WasmMatcher) SetInput(input string)
  • func (m *WasmMatcher) SetInputFromFile(filePath string) error

Constants

const (
	// Node type constants
	NodeTypeNonterminal = 0
	NodeTypeTerminal    = -1
	NodeTypeIter        = -2
)

const (
	InputBufferOffset = wasmPageSize
	InputBufferSize   = wasmPageSize
	MemoTableOffset   = InputBufferOffset + InputBufferSize
)

Constants for memory layout

Types

type CstNode

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

CstNode represents a node in the Concrete Syntax Tree

func NewCstNode

func NewCstNode(ruleNames []string, memory api.Memory, offset uint32) *CstNode

NewCstNode creates a new CstNode with the given parameters

func (*CstNode) Children

func (n *CstNode) Children() ([]*CstNode, error)

Children returns a slice of child nodes

func (*CstNode) IsIter

func (n *CstNode) IsIter() bool

IsIter returns true if this node represents an iteration

func (*CstNode) IsNonterminal

func (n *CstNode) IsNonterminal() bool

IsNonterminal returns true if this node represents a nonterminal

func (*CstNode) IsTerminal

func (n *CstNode) IsTerminal() bool

IsTerminal returns true if this node represents a terminal

func (*CstNode) MatchLength

func (n *CstNode) MatchLength() (uint32, error)

MatchLength returns the length of the matched text

func (*CstNode) RuleName

func (n *CstNode) RuleName() (string, error)

RuleName returns the name of the rule that created this node

func (*CstNode) Type

func (n *CstNode) Type() int32

Type returns the type of this node (0 for nonterminal, -1 for terminal, -2 for iter)

type WasmMatcher

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

WasmMatcher is a Go implementation of the JavaScript WasmMatcher class for Ohm

func NewWasmMatcher

func NewWasmMatcher(ctx context.Context) *WasmMatcher

func (*WasmMatcher) Close

func (m *WasmMatcher) Close() error

Close releases all resources

func (*WasmMatcher) GetCstRoot

func (m *WasmMatcher) GetCstRoot() (*CstNode, error)

GetCstRoot returns a CstNode object for the current parse tree

func (*WasmMatcher) GetInput

func (m *WasmMatcher) GetInput() string

func (*WasmMatcher) GetModule

func (m *WasmMatcher) GetModule() api.Module

GetModule returns the WebAssembly module

func (*WasmMatcher) LoadModule

func (m *WasmMatcher) LoadModule(wasmPath string) error

func (*WasmMatcher) Match

func (m *WasmMatcher) Match(ruleName ...string) (bool, error)

func (*WasmMatcher) SetInput

func (m *WasmMatcher) SetInput(input string)

func (*WasmMatcher) SetInputFromFile

func (m *WasmMatcher) SetInputFromFile(filePath string) error

SetInputFromFile reads input from a file and sets it as the current input