@[reducible, inline]

abbrev Lean.Parser.mkAtom (info : SourceInfo) (val : String) : Syntax

@[reducible, inline]

abbrev Lean.Parser.mkIdent (info : SourceInfo) (rawVal : Substring.Raw) (val : Name) : Syntax

def Lean.Parser.getNext (input : String) (pos : String.Pos.Raw) : Char

Return character after position pos

def Lean.Parser.maxPrec : Nat

Maximal (and function application) precedence. In the standard lean language, no parser has precedence higher than maxPrec.

Note that nothing prevents users from using a higher precedence, but we strongly discourage them from doing it.

def Lean.Parser.argPrec : Nat

def Lean.Parser.leadPrec : Nat

def Lean.Parser.minPrec : Nat

@[reducible, inline]

abbrev Lean.Parser.Token : Type

@[reducible, inline]

abbrev Lean.Parser.TokenTable : Type

@[reducible, inline]

abbrev Lean.Parser.SyntaxNodeKindSet : Type

def Lean.Parser.SyntaxNodeKindSet.insert (s : SyntaxNodeKindSet) (k : SyntaxNodeKind) : SyntaxNodeKindSet

structure Lean.Parser.InputContext : Type

Input string and related data. Recall that the FileMap is a helper structure for mapping String.Pos in the input string to line/column information.

• mk' :: (
• inputString : String
• fileName : String
• fileMap : FileMap
• endPos : String.Pos.Raw
• endPos_valid : self.endPos ≤ self.inputString.rawEndPos
• )

@[implicit_reducible]

instance Lean.Parser.instInhabitedInputContext : Inhabited InputContext

def Lean.Parser.InputContext.mk (input fileName : String) (endPos : String.Pos.Raw := input.rawEndPos) (endPos_valid : endPos ≤ input.rawEndPos := by simp) (fileMap : FileMap := FileMap.ofString input) : InputContext

@[deprecated "Call `InputContext.get`, `InputContext.get'`, `InputContext.next'`, and `InputContext.atEnd` directly" (since := "2025-08-21")]

def Lean.Parser.InputContext.input (c : InputContext) : String

def Lean.Parser.InputContext.atEnd (c : InputContext) (p : String.Pos.Raw) : Bool

Returns true if a specified byte position is greater than or equal to the position which points to the end of the input string. Otherwise, returns false.

@[inline]

def Lean.Parser.InputContext.get (c : InputContext) (p : String.Pos.Raw) : Char

Returns the character at position p of the input string. If p is not a valid position, returns the fallback value (default : Char), which is 'A', but does not panic.

theorem Lean.Parser.InputContext.not_atEnd_inputString {c : InputContext} {p : String.Pos.Raw} : ¬c.atEnd p = true → ¬String.Pos.Raw.atEnd c.inputString p = true

@[inline]

def Lean.Parser.InputContext.get' (c : InputContext) (p : String.Pos.Raw) (h : ¬c.atEnd p = true) : Char

Returns the character at position p of the input string. Returns (default : Char), which is 'A', if p is not a valid position.

Requires evidence, h, that p is within bounds instead of performing a run-time bounds check as in InputContext.get.

A typical pattern combines get' with a dependent if-expression to avoid the overhead of an additional bounds check. For example:

def getInBounds? (s : String) (p : String.Pos) : Option Char :=
  if h : s.atEnd p then none else some (s.get' p h)

Even with evidence of ¬ s.atEnd p, p may be invalid if a byte index points into the middle of a multi-byte UTF-8 character.

@[inline]

def Lean.Parser.InputContext.next (c : InputContext) (p : String.Pos.Raw) : String.Pos.Raw

Returns the next position in the input string after position p. If p is not a valid position or p = c.endPos, returns the position one byte after p.

A run-time bounds check is performed to determine whether p is at the end of the string. If a bounds check has already been performed, use InputContext.next' to avoid a repeated check.

@[inline]

def Lean.Parser.InputContext.next' (c : InputContext) (p : String.Pos.Raw) (h : ¬c.atEnd p = true) : String.Pos.Raw

Returns the next position in the input string after position p. The result is unspecified if p is not a valid position.

Requires evidence, h, that p is within bounds. No run-time bounds check is performed.

@[inline]

def Lean.Parser.InputContext.extract (c : InputContext) : String.Pos.Raw → String.Pos.Raw → String

Creates a new string that consists of the region of the input string delimited by the two positions.

The result is "" if the start position is greater than or equal to the end position or if the start position is at the end of the string. If either position is invalid (that is, if either points at the middle of a multi-byte UTF-8 character) then the result is unspecified.

@[inline]

def Lean.Parser.InputContext.substring (c : InputContext) (startPos stopPos : String.Pos.Raw) : Substring.Raw

Extracts a substring of the input string, bounded by startPos and stopPos.

@[inline]

def Lean.Parser.InputContext.getNext (input : InputContext) (pos : String.Pos.Raw) : Char

Return character after position pos

@[inline]

def Lean.Parser.InputContext.prev (c : InputContext) (pos : String.Pos.Raw) : String.Pos.Raw

Returns the character position prior to pos

structure Lean.Parser.ParserModuleContext : Type

Input context derived from elaboration of previous commands.

• env : Environment
• options : Options
• currNamespace : Name
• openDecls : List OpenDecl

structure Lean.Parser.CacheableParserContext : Type

Parser context parts that can be updated without invalidating the parser cache.

• prec : Nat
• quotDepth : Nat
• suppressInsideQuot : Bool
• savedPos? : Option String.Pos.Raw
• forbiddenTk? : Option Token

def Lean.Parser.instBEqCacheableParserContext.beq : CacheableParserContext → CacheableParserContext → Bool

@[implicit_reducible]

instance Lean.Parser.instBEqCacheableParserContext : BEq CacheableParserContext

structure Lean.Parser.ParserContextCoreextends Lean.Parser.InputContext, Lean.Parser.ParserModuleContext, Lean.Parser.CacheableParserContext : Type

Parser context updateable in adaptUncacheableContextFn.

• inputString : String
• fileName : String
• fileMap : FileMap
• endPos : String.Pos.Raw
• endPos_valid : self.endPos ≤ self.inputString.rawEndPos
• env : Environment
• options : Options
• currNamespace : Name
• openDecls : List OpenDecl
• prec : Nat
• quotDepth : Nat
• suppressInsideQuot : Bool
• savedPos? : Option String.Pos.Raw
• forbiddenTk? : Option Token
• tokens : TokenTable

structure Lean.Parser.ParserContextextends Lean.Parser.ParserContextCore : Type

Opaque parser context updateable using adaptCacheableContextFn and adaptUncacheableContextFn.

• inputString : String
• fileName : String
• fileMap : FileMap
• endPos : String.Pos.Raw
• endPos_valid : self.endPos ≤ self.inputString.rawEndPos
• env : Environment
• options : Options
• currNamespace : Name
• openDecls : List OpenDecl
• prec : Nat
• quotDepth : Nat
• suppressInsideQuot : Bool
• savedPos? : Option String.Pos.Raw
• forbiddenTk? : Option Token
• tokens : TokenTable

@[implicit_reducible]

instance Lean.Parser.instCoeParserContextInputContext : Coe ParserContext InputContext

def Lean.Parser.ParserContext.setEndPos (c : ParserContext) (endPos : String.Pos.Raw) (endPos_valid : endPos ≤ c.inputString.rawEndPos) : ParserContext

Modifies the ending position of a parser context.

structure Lean.Parser.Error : Type

• unexpectedTk : Syntax

  If not missing, used for lazily calculating unexpected message and range in mkErrorMessage. Otherwise, ParserState.pos is used as an empty range.

• unexpected : String
• expected : List String

def Lean.Parser.instInhabitedError.default : Error

@[implicit_reducible]

instance Lean.Parser.instInhabitedError : Inhabited Error

def Lean.Parser.instBEqError.beq : Error → Error → Bool

@[implicit_reducible]

instance Lean.Parser.instBEqError : BEq Error

def Lean.Parser.Error.toString (e : Error) : String

@[implicit_reducible]

instance Lean.Parser.Error.instToString : ToString Error

def Lean.Parser.Error.merge (e₁ e₂ : Error) : Error

structure Lean.Parser.TokenCacheEntry : Type

• startPos : String.Pos.Raw
• stopPos : String.Pos.Raw
• token : Syntax

structure Lean.Parser.ParserCacheKeyextends Lean.Parser.CacheableParserContext : Type

• prec : Nat
• quotDepth : Nat
• suppressInsideQuot : Bool
• savedPos? : Option String.Pos.Raw
• forbiddenTk? : Option Token
• parserName : Name
• pos : String.Pos.Raw

@[implicit_reducible]

instance Lean.Parser.instBEqParserCacheKey : BEq ParserCacheKey

def Lean.Parser.instBEqParserCacheKey.beq : ParserCacheKey → ParserCacheKey → Bool

@[implicit_reducible]

instance Lean.Parser.instHashableParserCacheKey : Hashable ParserCacheKey

structure Lean.Parser.ParserCacheEntry : Type

• stx : Syntax
• lhsPrec : Nat
• newPos : String.Pos.Raw
• errorMsg : Option Error

structure Lean.Parser.ParserCache : Type

• tokenCache : TokenCacheEntry
• parserCache : Std.HashMap ParserCacheKey ParserCacheEntry

def Lean.Parser.initCacheForInput (input : String) : ParserCache

structure Lean.Parser.SyntaxStack : Type

A syntax array with an inaccessible prefix, used for sound caching.

• raw : Array Lean.Syntax
• drop : Nat

def Lean.Parser.SyntaxStack.toSubarray (stack : SyntaxStack) : Subarray Syntax

def Lean.Parser.SyntaxStack.empty : SyntaxStack

def Lean.Parser.SyntaxStack.size (stack : SyntaxStack) : Nat

def Lean.Parser.SyntaxStack.isEmpty (stack : SyntaxStack) : Bool

def Lean.Parser.SyntaxStack.shrink (stack : SyntaxStack) (n : Nat) : SyntaxStack

def Lean.Parser.SyntaxStack.push (stack : SyntaxStack) (a : Syntax) : SyntaxStack

def Lean.Parser.SyntaxStack.pop (stack : SyntaxStack) : SyntaxStack

def Lean.Parser.SyntaxStack.back (stack : SyntaxStack) : Syntax

def Lean.Parser.SyntaxStack.get! (stack : SyntaxStack) (i : Nat) : Syntax

def Lean.Parser.SyntaxStack.extract (stack : SyntaxStack) (start stop : Nat) : Array Syntax

@[implicit_reducible]

instance Lean.Parser.SyntaxStack.instHAppendArraySyntax : HAppend SyntaxStack (Array Syntax) SyntaxStack

structure Lean.Parser.ParserState : Type

• stxStack : SyntaxStack
• lhsPrec : Nat

  Set to the precedence of the preceding (not surrounding) parser by runLongestMatchParser for the use of checkLhsPrec in trailing parsers. Note that with chaining, the preceding parser can be another trailing parser: in 1 * 2 + 3, the preceding parser is '*' when '+' is executed.

• pos : String.Pos.Raw
• cache : ParserCache
• errorMsg : Option Error
• recoveredErrors : Array (String.Pos.Raw × SyntaxStack × Error)

@[inline]

def Lean.Parser.ParserState.hasError (s : ParserState) : Bool

def Lean.Parser.ParserState.stackSize (s : ParserState) : Nat

def Lean.Parser.ParserState.restore (s : ParserState) (iniStackSz : Nat) (iniPos : String.Pos.Raw) : ParserState

def Lean.Parser.ParserState.setPos (s : ParserState) (pos : String.Pos.Raw) : ParserState

def Lean.Parser.ParserState.setCache (s : ParserState) (cache : ParserCache) : ParserState

def Lean.Parser.ParserState.pushSyntax (s : ParserState) (n : Syntax) : ParserState

def Lean.Parser.ParserState.popSyntax (s : ParserState) : ParserState

def Lean.Parser.ParserState.shrinkStack (s : ParserState) (iniStackSz : Nat) : ParserState

def Lean.Parser.ParserState.next (s : ParserState) (c : ParserContext) (pos : String.Pos.Raw) : ParserState

def Lean.Parser.ParserState.next' (s : ParserState) (c : ParserContext) (pos : String.Pos.Raw) (h : ¬c.atEnd pos = true) : ParserState

def Lean.Parser.ParserState.mkNode (s : ParserState) (k : SyntaxNodeKind) (iniStackSz : Nat) : ParserState

def Lean.Parser.ParserState.mkTrailingNode (s : ParserState) (k : SyntaxNodeKind) (iniStackSz : Nat) : ParserState

def Lean.Parser.ParserState.allErrors (s : ParserState) : Array (String.Pos.Raw × SyntaxStack × Error)

@[inline]

def Lean.Parser.ParserState.setError (s : ParserState) (e : Error) : ParserState

def Lean.Parser.ParserState.mkError (s : ParserState) (msg : String) : ParserState

def Lean.Parser.ParserState.mkUnexpectedError (s : ParserState) (msg : String) (expected : List String := []) (pushMissing : Bool := true) : ParserState

def Lean.Parser.ParserState.mkEOIError (s : ParserState) (expected : List String := []) : ParserState

def Lean.Parser.ParserState.mkErrorsAt (s : ParserState) (ex : List String) (pos : String.Pos.Raw) (initStackSz? : Option Nat := none) : ParserState

def Lean.Parser.ParserState.mkErrorAt (s : ParserState) (msg : String) (pos : String.Pos.Raw) (initStackSz? : Option Nat := none) : ParserState

def Lean.Parser.ParserState.mkUnexpectedTokenErrors (s : ParserState) (ex : List String) (iniPos : String.Pos.Raw := 0) : ParserState

Reports given 'expected' messages at range of top stack element (assumed to be a single token). Replaces the element with missing and resets position to the token position. iniPos can be specified to avoid this position lookup but still must be identical to the token position.

def Lean.Parser.ParserState.mkUnexpectedTokenError (s : ParserState) (msg : String) (iniPos : String.Pos.Raw := 0) : ParserState

Reports given 'expected' message at range of top stack element (assumed to be a single token). Replaces the element with missing and resets position to the token position. iniPos can be specified to avoid this position lookup but still must be identical to the token position.

def Lean.Parser.ParserState.mkUnexpectedErrorAt (s : ParserState) (msg : String) (pos : String.Pos.Raw) : ParserState

def Lean.Parser.ParserState.toErrorMsg (ctx : InputContext) (s : ParserState) : String

def Lean.Parser.ParserFn : Type

@[implicit_reducible]

instance Lean.Parser.instInhabitedParserFn : Inhabited ParserFn

inductive Lean.Parser.FirstTokens : Type

• epsilon : FirstTokens
• unknown : FirstTokens
• tokens : List Token → FirstTokens
• optTokens : List Token → FirstTokens

def Lean.Parser.instInhabitedFirstTokens.default : FirstTokens

@[implicit_reducible]

instance Lean.Parser.instInhabitedFirstTokens : Inhabited FirstTokens

def Lean.Parser.FirstTokens.seq : FirstTokens → FirstTokens → FirstTokens

def Lean.Parser.FirstTokens.toOptional : FirstTokens → FirstTokens

def Lean.Parser.FirstTokens.merge : FirstTokens → FirstTokens → FirstTokens

def Lean.Parser.FirstTokens.toStr : FirstTokens → String

@[implicit_reducible]

instance Lean.Parser.FirstTokens.instToString : ToString FirstTokens

structure Lean.Parser.ParserInfo : Type

• collectTokens : List Token → List Token
• collectKinds : SyntaxNodeKindSet → SyntaxNodeKindSet
• firstTokens : FirstTokens

def Lean.Parser.instInhabitedParserInfo.default : ParserInfo

@[implicit_reducible]

instance Lean.Parser.instInhabitedParserInfo : Inhabited ParserInfo

structure Lean.Parser.Parser : Type

• info : ParserInfo
• fn : ParserFn

@[implicit_reducible]

instance Lean.Parser.instInhabitedParser : Inhabited Parser

def Lean.Parser.instInhabitedParser.default : Parser

@[reducible, inline]

abbrev Lean.Parser.TrailingParser : Type

@[inline]

def Lean.Parser.withFn (f : ParserFn → ParserFn) (p : Parser) : Parser

Create a simple parser combinator that inherits the info of the nested parser.

def Lean.Parser.adaptCacheableContextFn (f : CacheableParserContext → CacheableParserContext) (p : ParserFn) : ParserFn

def Lean.Parser.adaptCacheableContext (f : CacheableParserContext → CacheableParserContext) : Parser → Parser

def Lean.Parser.withResetCacheFn (p : ParserFn) : ParserFn

Run p with a fresh cache, restore outer cache afterwards. p may access the entire syntax stack.

def Lean.Parser.withResetCache : Parser → Parser

Run p with a fresh cache, restore outer cache afterwards. p may access the entire syntax stack.

def Lean.Parser.adaptUncacheableContextFn (f : ParserContextCore → ParserContextCore) (p : ParserFn) : ParserFn

Run p under the given context transformation with a fresh cache (see also withResetCacheFn).

def Lean.Parser.withCacheFn (parserName : Name) (p : ParserFn) : ParserFn

Run p and record result in parser cache for any further invocation with this parserName, parser context, and parser state. p cannot access syntax stack elements pushed before the invocation in order to make caching independent of parser history. As this excludes trailing parsers from being cached, we also reset lhsPrec, which is not read but set by leading parsers, to 0 in order to increase cache hits. Finally, errorMsg is also reset to none as a leading parser should not be called in the first place if there was an error.

def Lean.Parser.withCache (parserName : Name) : Parser → Parser

Run p and record result in parser cache for any further invocation with this parserName, parser context, and parser state. p cannot access syntax stack elements pushed before the invocation in order to make caching independent of parser history. As this excludes trailing parsers from being cached, we also reset lhsPrec, which is not read but set by leading parsers, to 0 in order to increase cache hits. Finally, errorMsg is also reset to none as a leading parser should not be called in the first place if there was an error.

def Lean.Parser.ParserFn.run (p : ParserFn) (ictx : InputContext) (pmctx : ParserModuleContext) (tokens : TokenTable) (s : ParserState) : ParserState