Parser

Documentation

Index

• Constants
• func FullParse(grammar *ParserGrammar, source *cds.Stream[*gr.LeafToken], ...) ([]*gr.TokenTree, error)
• func ParseBranch(parser *Parser, source *cds.Stream[*gr.LeafToken]) ([]*gr.TokenTree, error)
• type CurrentEval
  • func NewCurrentEval() *CurrentEval
  • func (ce *CurrentEval) Accept() bool
  • func (ce *CurrentEval) ActOnDecision(decision cs.HelperElem, source *cds.Stream[*gr.LeafToken]) error
  • func (ce *CurrentEval) Copy() uc.Copier
  • func (ce *CurrentEval) GetParseTree() ([]*gr.TokenTree, error)
  • func (ce *CurrentEval) Parse(source *cds.Stream[*gr.LeafToken], dt *cs.ConflictSolver) ([]*CurrentEval, error)
• type ErrNoAccept
  • func NewErrNoAccept() *ErrNoAccept
  • func (e *ErrNoAccept) Error() string
• type ErrNothingWasParsed
  • func NewErrNothingWasParsed() *ErrNothingWasParsed
  • func (e *ErrNothingWasParsed) Error() string
• type ErrUnknownAction
  • func NewErrUnknownAction(action any) *ErrUnknownAction
  • func (e *ErrUnknownAction) Error() string
• type Parser
  • func NewParser(grammar *ParserGrammar) (*Parser, error)
  • func (p *Parser) GetParseTree() ([]*gr.TokenTree, error)
  • func (p *Parser) Parse(source *cds.Stream[*gr.LeafToken]) error
• type ParserGrammar
  • func NewParserGrammar(rules string) (*ParserGrammar, error)
  • func (g *ParserGrammar) GetProductions() []*gr.Production
  • func (g *ParserGrammar) GetSymbols() []string
  • func (g *ParserGrammar) ProductionMatch(at int, stack *ds.DoubleStack[gr.Tokener]) []*gr.MatchedResult[*gr.NonLeafToken]

Constants

const (
	Indentation string = "|  "
)

Functions

func FullParse

func FullParse(grammar *ParserGrammar, source *cds.Stream[*gr.LeafToken], dt *cs.ConflictSolver) ([]*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 ParseBranch

func ParseBranch(parser *Parser, source *cds.Stream[*gr.LeafToken]) ([]*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 struct {
	// contains filtered or unexported fields
}

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

func NewCurrentEval

func NewCurrentEval() *CurrentEval

NewCurrentEval creates a new current evaluation.

Returns:

• *CurrentEval: A new current evaluation.

func (*CurrentEval) Accept

func (ce *CurrentEval) 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) ActOnDecision

func (ce *CurrentEval) ActOnDecision(decision cs.HelperElem, source *cds.Stream[*gr.LeafToken]) 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) Copy

func (ce *CurrentEval) Copy() uc.Copier

Copy creates a copy of the current evaluation.

Returns:

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

func (*CurrentEval) GetParseTree

func (ce *CurrentEval) 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:

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

func (*CurrentEval) Parse

func (ce *CurrentEval) Parse(source *cds.Stream[*gr.LeafToken], dt *cs.ConflictSolver) ([]*CurrentEval, 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 ErrNothingWasParsed

type ErrNothingWasParsed struct{}

ErrNothingWasParsed is an error that is returned when the parser does not parse anything.

func NewErrNothingWasParsed

func NewErrNothingWasParsed() *ErrNothingWasParsed

NewErrNothingWasParsed creates a new ErrNothingWasParsed error.

Returns:

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

func (*ErrNothingWasParsed) Error

func (e *ErrNothingWasParsed) Error() string

Error returns the error message: "nothing was parsed".

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 Parser

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

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

func NewParser

func NewParser(grammar *ParserGrammar) (*Parser, 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:

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

func (*Parser) GetParseTree

func (p *Parser) 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.

func (*Parser) Parse

func (p *Parser) Parse(source *cds.Stream[*gr.LeafToken]) error

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

Returns:

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

type ParserGrammar

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

ParserGrammar represents a context-free grammar.

func NewParserGrammar

func NewParserGrammar(rules string) (*ParserGrammar, error)

NewParserGrammar 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 (*ParserGrammar) GetProductions

func (g *ParserGrammar) GetProductions() []*gr.Production

GetProductions returns a slice of Production in the grammar.

Returns:

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

func (*ParserGrammar) GetSymbols

func (g *ParserGrammar) GetSymbols() []string

GetSymbols returns a slice of symbols in the grammar.

Returns:

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

func (*ParserGrammar) ProductionMatch

func (g *ParserGrammar) ProductionMatch(at int, stack *ds.DoubleStack[gr.Tokener]) []*gr.MatchedResult[*gr.NonLeafToken]

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.