Parser

Documentation

Index

• Constants
• func FullParse[T gr.TokenTyper](grammar *Grammar[T], source *cds.Stream[*gr.Token[T]], ...) ([]*gr.TokenTree, error)
• func Parse[T gr.TokenTyper](p *Parser[T], source *cds.Stream[*gr.Token[T]]) error
• func ParseBranch[T gr.TokenTyper](parser *Parser[T], source *cds.Stream[*gr.Token[T]]) ([]*gr.TokenTree, error)
• type CurrentEval
  • func NewCurrentEval[T gr.TokenTyper]() *CurrentEval[T]
  • func (ce *CurrentEval[T]) Accept() bool
  • func (ce *CurrentEval[T]) ActOnDecision(decision cs.HelperElem[T], source *cds.Stream[*gr.Token[T]]) error
  • func (ce *CurrentEval[T]) Copy() uc.Copier
  • func (ce *CurrentEval[T]) GetParseTree() ([]*gr.TokenTree, error)
  • func (ce *CurrentEval[T]) Parse(source *cds.Stream[*gr.Token[T]], dt *cs.ConflictSolver[T]) ([]*CurrentEval[T], error)
• type ErrNoAccept
  • func NewErrNoAccept() *ErrNoAccept
  • func (e *ErrNoAccept) Error() string
• type ErrUnknownAction
  • func NewErrUnknownAction(action any) *ErrUnknownAction
  • func (e *ErrUnknownAction) Error() string
• type Grammar
  • func NewGrammar[T gr.TokenTyper]() (*Grammar[T], error)
  • func (g *Grammar[T]) AddRule(lhs T, rhss []T) error
  • func (g *Grammar[T]) GetProductions() []*gr.Production[T]
  • func (g *Grammar[T]) GetSymbols() []T
  • func (g *Grammar[T]) ProductionMatch(at int, stack *ud.History[lls.Stacker[*gr.Token[T]]]) []*gr.MatchedResult[T]
• type Parser
  • func NewParser[T gr.TokenTyper](grammar *Grammar[T]) (*Parser[T], error)
  • func (p *Parser[T]) GetParseTree() ([]*gr.TokenTree, error)

Constants

const (
	Indentation string = "|  "
)

Functions

func FullParse

func FullParse[T gr.TokenTyper](grammar *Grammar[T], source *cds.Stream[*gr.Token[T]], dt *cs.ConflictSolver[T]) ([]*gr.TokenTree, error)

FullParse parses the input stream using the given grammar and decision function. It is a convenience function intended for simple parsing tasks.

Parameters:

• grammar: The grammar that the parser will use.
• inputStream: The input stream that the parser will parse.
• decisionFunc: The decision function that the parser will use.

Returns:

• []gr.NonLeafToken: The parse tree.
• error: An error if the input stream could not be parsed.

func Parse

func Parse[T gr.TokenTyper](p *Parser[T], source *cds.Stream[*gr.Token[T]]) error

Parse parses the input stream using the parser's decision function.

Parameters:

• p: The parser to use.
• source: The input stream to parse.

Returns:

• error: An error if the input stream could not be parsed.

func ParseBranch

func ParseBranch[T gr.TokenTyper](parser *Parser[T], source *cds.Stream[*gr.Token[T]]) ([]*gr.TokenTree, error)

ParseBranch is a function that, given a parser and an input stream of tokens, returns a slice of non-leaf tokens.

Parameters:

• parser: The parser to use.
• inputStream: The input stream of tokens to parse.

Returns:

• []gr.NonLeafToken: A slice of non-leaf tokens.
• error: An error if the branch cannot be parsed.

Types

type CurrentEval

type CurrentEval[T gr.TokenTyper] struct {
	// contains filtered or unexported fields
}

CurrentEval is a struct that represents the current evaluation of the parser.

func NewCurrentEval

func NewCurrentEval[T gr.TokenTyper]() *CurrentEval[T]

NewCurrentEval creates a new current evaluation.

Returns:

• *CurrentEval: A new current evaluation.

func (*CurrentEval[T]) Accept

func (ce *CurrentEval[T]) Accept() bool

Accept returns true if the current evaluation has accepted the input stream.

Returns:

• bool: True if the current evaluation has accepted the input stream.

func (*CurrentEval[T]) ActOnDecision

func (ce *CurrentEval[T]) ActOnDecision(decision cs.HelperElem[T], source *cds.Stream[*gr.Token[T]]) error

ActOnDecision acts on a decision that the parser has made.

Parameters:

• decision: The decision that the parser has made.
• source: The source of the input stream.

Returns:

• bool: True if the parser has accepted the input stream.
• error: An error if the parser could not act on the decision.

func (*CurrentEval[T]) Copy

func (ce *CurrentEval[T]) Copy() uc.Copier

Copy creates a copy of the current evaluation.

Returns:

• uc.Copier: A copy of the current evaluation.

func (*CurrentEval[T]) GetParseTree

func (ce *CurrentEval[T]) GetParseTree() ([]*gr.TokenTree, error)

GetParseTree returns the parse tree that the parser has generated.

Parse() must be called before calling this method. If it is not, an error will be returned.

Returns:

• []*gr.TokenTree: A slice of parse trees.
• error: An error if the parse tree could not be retrieved.

Errors:

• *uc.ErrInvalidUsage: If Parse() has not been called.
• *gr.ErrCycleDetected: A cycle is detected in the token tree.
• *uc.ErrInvalidParameter: The top of the stack is nil.
• *gr.ErrUnknowToken: The root is not a known token.

func (*CurrentEval[T]) Parse

func (ce *CurrentEval[T]) Parse(source *cds.Stream[*gr.Token[T]], dt *cs.ConflictSolver[T]) ([]*CurrentEval[T], error)

Parse parses the input stream using the parser's decision table.

Parameters:

• source: The source of the input stream.
• dt: The decision table to use.

Returns:

• []*CurrentEval: A slice of current evaluations.
• error: An error if the input stream could not be parsed.

type ErrNoAccept

type ErrNoAccept struct{}

ErrNoAccept is an error that is returned when the parser reaches the end of the input stream without accepting the input stream.

func NewErrNoAccept

func NewErrNoAccept() *ErrNoAccept

NewErrNoAccept creates a new ErrNoAccept error.

Returns:

• *ErrNoAccept: A pointer to the new ErrNoAccept error.

func (*ErrNoAccept) Error

func (e *ErrNoAccept) Error() string

Error is a method of the error interface.

Returns:

• string: The error message.

type ErrUnknownAction

type ErrUnknownAction struct {

	// Action is the action that was attempted.
	Action any
}

ErrUnknownAction is an error that is returned when the parser encounters an unknown action.

func NewErrUnknownAction

func NewErrUnknownAction(action any) *ErrUnknownAction

NewErrUnknownAction creates a new ErrUnknownAction error.

Parameters:

• action: The action that was attempted.

Returns:

• *ErrUnknownAction: A pointer to the new ErrUnknownAction error.

func (*ErrUnknownAction) Error

func (e *ErrUnknownAction) Error() string

Error is a method of the error interface.

Returns:

• string: The error message.

type Grammar

type Grammar[T gr.TokenTyper] struct {
	// contains filtered or unexported fields
}

Grammar represents a context-free grammar.

func NewGrammar

func NewGrammar[T gr.TokenTyper]() (*Grammar[T], error)

NewGrammar is a constructor of an empty ParserGrammar.

A context-free grammar is a set of productions, each of which consists of a non-terminal symbol and a sequence of symbols.

The non-terminal symbol is the left-hand side of the production, and the sequence of symbols is the right-hand side of the production.

The grammar also contains a set of symbols, which are the non-terminal and terminal symbols in the grammar.

Returns:

• *ParserGrammar: A new empty ParserGrammar.

func (*Grammar[T]) AddRule

func (g *Grammar[T]) AddRule(lhs T, rhss []T) error

AddRule adds a new rule to the grammar.

Parameters:

• lhs: The left-hand side of the production.
• rhss: The right-hand side of the production.

Returns:

• error: An error if there was a problem adding the rule.

func (*Grammar[T]) GetProductions

func (g *Grammar[T]) GetProductions() []*gr.Production[T]

GetProductions returns a slice of Production in the grammar.

Returns:

• []*Production: A slice of Production in the grammar.

func (*Grammar[T]) GetSymbols

func (g *Grammar[T]) GetSymbols() []T

GetSymbols returns a slice of symbols in the grammar.

Returns:

• []T: A slice of symbols in the grammar.

func (*Grammar[T]) ProductionMatch

func (g *Grammar[T]) ProductionMatch(at int, stack *ud.History[lls.Stacker[*gr.Token[T]]]) []*gr.MatchedResult[T]

ProductionMatch returns a slice of MatchedResult that match the input token.

Parameters:

• at: The position in the input string.
• stack: The input stream to match. Refers to Productioner.Match.

Returns:

• []MatchedResult: A slice of MatchedResult that match the input token.

type Parser

type Parser[T gr.TokenTyper] struct {
	// contains filtered or unexported fields
}

Parser is a parser that uses a stack to parse a stream of tokens.

func NewParser

func NewParser[T gr.TokenTyper](grammar *Grammar[T]) (*Parser[T], error)

NewParser creates a new parser with the given grammar.

Parameters:

• grammar: The grammar that the parser will use.

Returns:

• *Parser: A pointer to the new parser.
• error: An error if the parser could not be created.

Errors:

• *uc.ErrInvalidParameter: The grammar is nil.
• *gr.ErrNoProductionRulesFound: No production rules are found in the grammar.

func (*Parser[T]) GetParseTree

func (p *Parser[T]) GetParseTree() ([]*gr.TokenTree, error)

GetParseTree returns the parse tree that the parser has generated.

Parse() must be called before calling this method. If it is not, an error will be returned.

Returns:

• []*gr.TokenTree: A slice of parse trees.
• error: An error if the parse tree could not be retrieved.