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// Copyright (c) 2012-2022 The ANTLR Project. All rights reserved.
// Use of this file is governed by the BSD 3-clause license that
// can be found in the LICENSE.txt file in the project root.
package antlr
// RuleContext is a record of a single rule invocation. It knows
// which context invoked it, if any. If there is no parent context, then
// naturally the invoking state is not valid. The parent link
// provides a chain upwards from the current rule invocation to the root
// of the invocation tree, forming a stack.
//
// We actually carry no information about the rule associated with this context (except
// when parsing). We keep only the state number of the invoking state from
// the [ATN] submachine that invoked this. Contrast this with the s
// pointer inside [ParserRuleContext] that tracks the current state
// being "executed" for the current rule.
//
// The parent contexts are useful for computing lookahead sets and
// getting error information.
//
// These objects are used during parsing and prediction.
// For the special case of parsers, we use the struct
// [ParserRuleContext], which embeds a RuleContext.
//
// @see ParserRuleContext
type RuleContext interface {
RuleNode
GetInvokingState() int
SetInvokingState(int)
GetRuleIndex() int
IsEmpty() bool
GetAltNumber() int
SetAltNumber(altNumber int)
String([]string, RuleContext) string
}
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