feat: update ParseCursor

CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
-- Renamed `CustomLexerContext` to `CustomLexerCursor` and separated it from the
+- Renamed `CustomLexerContext` to `LexCursor` and separated it from the
+  `context.Context` type.
+- Renamed `ParserContext` to `ParseCursor` and separated it from the
   `context.Context` type.
 
 ## [0.3.0] - 2026-01-25

README.md

@@ -130,9 +130,9 @@ in addition to the underlying reader's position. When the token has been fully
 processed it can be emitted to a channel for further processing by the `Parser`.
 
 Developers implement the token processing portion of the lexer by implementing
-`LexState` interface for each relevant lexer state. A `CustomLexerCursor` is
-passed to each `LexState` during processing and includes a number of methods
-that can be used to advance through the input text.
+`LexState` interface for each relevant lexer state. A `LexCursor` is passed to
+each `LexState` during processing and includes a number of methods that can be
+used to advance through the input text.
 
 For example, consider the following simple template language.
 
@@ -211,7 +211,7 @@ type LexState interface {
     // Run returns the next state to transition to or an error. If the returned
     // next state is nil or the returned error is io.EOF then the Lexer
     // finishes processing normally.
-    Run(context.Context, *CustomLexerCursor) (LexState, error)
+    Run(context.Context, *LexCursor) (LexState, error)
 }
 ```
 
@@ -238,23 +238,23 @@ advancing over the text.
 
 ```go
 // lexText tokenizes normal text.
-func lexText(ctx context.Context, c *lexparse.CustomLexerCursor) (lexparse.LexState, error) {
+func lexText(ctx context.Context, cur *lexparse.LexCursor) (lexparse.LexState, error) {
     for {
-        p := c.PeekN(2)
+        p := cur.PeekN(2)
         switch string(p) {
         case tokenBlockStart, tokenVarStart:
-            if c.Width() > 0 {
-                c.Emit(lexTypeText)
+            if cur.Width() > 0 {
+                cur.Emit(lexTypeText)
             }
             return lexparse.LexStateFn(lexCode), nil
         default:
         }
 
         // Advance the input.
-        if !c.Advance() {
+        if !cur.Advance() {
             // End of input. Emit the text up to this point.
-            if c.Width() > 0 {
-                c.Emit(lexTypeText)
+            if cur.Width() > 0 {
+                cur.Emit(lexTypeText)
             }
             return nil, nil
         }
@@ -326,7 +326,7 @@ flowchart-elk TD
 
 Similar to the lexer API, each parser state is represented by an object
 implementing the `ParseState` interface. It contains only a single `Run` method
-which handles processing input tokens while in that state. A `ParserContext` is
+which handles processing input tokens while in that state. A `ParseCursor` is
 passed to each `ParseState` during processing and includes a number of methods
 that can be used to examine the current token, advance to the next token, and
 manipulate the AST.
@@ -335,10 +335,12 @@ manipulate the AST.
 // ParseState is the state of the current parsing state machine. It defines the
 // logic to process the current state and returns the next state.
 type ParseState[V comparable] interface {
-    // Run returns the next state to transition to or an error. If the returned
-    // next state is nil or the returned error is io.EOF then the Lexer
-    // finishes processing normally.
-    Run(*ParserContext[V]) (ParseState[V], error)
+    // Run executes the logic at the current state, returning an error if one is
+    // encountered. Implementations are expected to add new Node objects to
+    // the AST using ParseCursor.Push or ParseCursor.Node. As necessary, new
+    // parser state should be pushed onto the stack as needed using
+    // Parser.PushState.
+    Run(ctx context.Context, cur *ParseCursor[V]) error
 }
 ```
 
@@ -377,16 +379,16 @@ Here we push the later relevant expected state onto the parser's stack.
 
 ```go
 // parseSeq delegates to another parse function based on token type.
-func parseSeq(ctx *lexparse.ParserContext[*tmplNode]) error {
-    token := ctx.Peek()
+func parseSeq(ctx context.Context, cur *lexparse.ParseCursor[*tmplNode]) error {
+    token := cur.Peek(ctx)
 
     switch token.Type {
     case lexTypeText:
-        ctx.PushState(lexparse.ParseStateFn(parseText))
+        cur.PushState(lexparse.ParseStateFn(parseText))
     case lexTypeVarStart:
-        ctx.PushState(lexparse.ParseStateFn(parseVarStart))
+        cur.PushState(lexparse.ParseStateFn(parseVarStart))
     case lexTypeBlockStart:
-        ctx.PushState(lexparse.ParseStateFn(parseBlockStart))
+        cur.PushState(lexparse.ParseStateFn(parseBlockStart))
     }
 
     return nil
@@ -399,11 +401,11 @@ are pushed in reverse order so that they are handled in the order listed.
 
 ```go
 // parseVarStart handles var start (e.g. '{{').
-func parseVarStart(ctx *lexparse.ParserContext[*tmplNode]) error {
+func parseVarStart(ctx context.Context, cur *lexparse.ParseCursor[*tmplNode]) error {
     // Consume the var start token.
-    _ = ctx.Next()
+    _ = cur.Next(ctx)
 
-    ctx.PushState(
+    cur.PushState(
         lexparse.ParseStateFn(parseVar),
         lexparse.ParseStateFn(parseVarEnd),
     )

custom.go

@@ -35,111 +35,111 @@ const EOF rune = -1
 type LexState interface {
 	// Run returns the next state to transition to or an error. If the returned
 	// error is io.EOF then the Lexer finishes processing normally.
-	Run(ctx context.Context, cursor *CustomLexerCursor) (LexState, error)
+	Run(ctx context.Context, cur *LexCursor) (LexState, error)
 }
 
 type lexFnState struct {
-	f func(context.Context, *CustomLexerCursor) (LexState, error)
+	f func(context.Context, *LexCursor) (LexState, error)
 }
 
 // Run implements [LexState.Run].
 //
 //nolint:ireturn // Returning interface required to satisfy [LexState.Run]
-func (s *lexFnState) Run(ctx context.Context, cursor *CustomLexerCursor) (LexState, error) {
-	return s.f(ctx, cursor)
+func (s *lexFnState) Run(ctx context.Context, cur *LexCursor) (LexState, error) {
+	return s.f(ctx, cur)
 }
 
 // LexStateFn creates a State from the given Run function.
 //
 //nolint:ireturn // Returning interface required to satisfy [LexState.Run]
-func LexStateFn(f func(context.Context, *CustomLexerCursor) (LexState, error)) LexState {
+func LexStateFn(f func(context.Context, *LexCursor) (LexState, error)) LexState {
 	return &lexFnState{f}
 }
 
-// CustomLexerCursor is a type that allows for processing the input for the
-// CustomLexer. It provides methods to advance the reader, emit tokens, and
+// LexCursor is a type that allows for processing the input for a
+// [CustomLexer]. It provides methods to advance the reader, emit tokens, and
 // manage the current token being processed. It is designed to be used within
 // the [LexState.Run] method to allow the state implementation to interact with
 // the lexer without exposing the full CustomLexer implementation.
-type CustomLexerCursor struct {
+type LexCursor struct {
 	l *CustomLexer
 }
 
-// NewCustomLexerCursor creates a new CustomLexerCursor.
-func NewCustomLexerCursor(l *CustomLexer) *CustomLexerCursor {
-	return &CustomLexerCursor{
+// NewLexCursor creates a new [LexCursor].
+func NewLexCursor(l *CustomLexer) *LexCursor {
+	return &LexCursor{
 		l: l,
 	}
 }
 
 // Advance attempts to advance the underlying reader a single rune and returns
 // true if actually advanced. The current token cursor position is not updated.
-func (c *CustomLexerCursor) Advance() bool {
+func (c *LexCursor) Advance() bool {
 	return c.l.advance(1, false) == 1
 }
 
 // AdvanceN attempts to advance the underlying reader n runes and returns the
 // number actually advanced. The current token cursor position is not updated.
-func (c *CustomLexerCursor) AdvanceN(n int) int {
+func (c *LexCursor) AdvanceN(n int) int {
 	return c.l.advance(n, false)
 }
 
 // Cursor returns the current position of the underlying cursor marking the
 // beginning of the current token being processed.
-func (c *CustomLexerCursor) Cursor() Position {
+func (c *LexCursor) Cursor() Position {
 	return c.l.cursor
 }
 
 // Discard attempts to discard the next rune, advancing the current token
 // cursor, and returns true if actually discarded.
-func (c *CustomLexerCursor) Discard() bool {
+func (c *LexCursor) Discard() bool {
 	return c.l.advance(1, true) == 1
 }
 
 // DiscardN attempts to discard n runes, advancing the current token cursor
 // position, and returns the number actually discarded.
-func (c *CustomLexerCursor) DiscardN(n int) int {
+func (c *LexCursor) DiscardN(n int) int {
 	return c.l.advance(n, true)
 }
 
 // DiscardTo searches the input for one of the given search strings, advancing
 // the reader, and stopping when one of the strings is found. The token cursor
 // is advanced and data prior to the search string is discarded. The string
 // found is returned. If no match is found an empty string is returned.
-func (c *CustomLexerCursor) DiscardTo(query []string) string {
+func (c *LexCursor) DiscardTo(query []string) string {
 	return c.l.discardTo(query)
 }
 
 // Emit emits the token between the current cursor position and reader
 // position and returns the token. If the lexer is not currently active, this
 // is a no-op. This advances the current token cursor.
-func (c *CustomLexerCursor) Emit(typ TokenType) *Token {
+func (c *LexCursor) Emit(typ TokenType) *Token {
 	return c.l.emit(typ)
 }
 
 // Find searches the input for one of the given search strings, advancing the
 // reader, and stopping when one of the strings is found. The token cursor is
 // not advanced. The string found is returned. If no match is found an empty
 // string is returned.
-func (c *CustomLexerCursor) Find(query []string) string {
+func (c *LexCursor) Find(query []string) string {
 	return c.l.find(query)
 }
 
 // Ignore ignores the previous input and resets the token start position to
 // the current reader position.
-func (c *CustomLexerCursor) Ignore() {
+func (c *LexCursor) Ignore() {
 	c.l.ignore()
 }
 
 // NextRune returns the next rune of input, advancing the reader while not
 // advancing the token cursor.
-func (c *CustomLexerCursor) NextRune() rune {
+func (c *LexCursor) NextRune() rune {
 	return c.l.nextRune()
 }
 
 // Peek returns the next rune from the buffer without advancing the reader or
 // current token cursor.
-func (c *CustomLexerCursor) Peek() rune {
+func (c *LexCursor) Peek() rune {
 	p := c.PeekN(1)
 	if len(p) < 1 {
 		return EOF
@@ -151,23 +151,23 @@ func (c *CustomLexerCursor) Peek() rune {
 // PeekN returns the next n runes from the buffer without advancing the reader
 // or current token cursor. PeekN may return fewer runes than requested if an
 // error occurs or at end of input.
-func (c *CustomLexerCursor) PeekN(n int) []rune {
+func (c *LexCursor) PeekN(n int) []rune {
 	return c.l.peekN(n)
 }
 
 // Pos returns the current position of the underlying reader.
-func (c *CustomLexerCursor) Pos() Position {
+func (c *LexCursor) Pos() Position {
 	return c.l.pos
 }
 
 // Token returns the current token value.
-func (c *CustomLexerCursor) Token() string {
+func (c *LexCursor) Token() string {
 	return c.l.b.String()
 }
 
 // Width returns the current width of the token being processed. It is
 // equivalent to l.Pos().Offset - l.Cursor().Offset.
-func (c *CustomLexerCursor) Width() int {
+func (c *LexCursor) Width() int {
 	return c.l.pos.Offset - c.l.cursor.Offset
 }
 
@@ -246,7 +246,7 @@ func (l *CustomLexer) NextToken(ctx context.Context) *Token {
 		return l.newToken(TokenTypeEOF)
 	}
 
-	cursor := NewCustomLexerCursor(l)
+	cur := NewLexCursor(l)
 
 	// If we have no tokens to return, we need to run the current state.
 	for len(l.buf) == 0 && l.state != nil {
@@ -261,7 +261,7 @@ func (l *CustomLexer) NextToken(ctx context.Context) *Token {
 
 		var err error
 
-		l.state, err = l.state.Run(ctx, cursor)
+		l.state, err = l.state.Run(ctx, cur)
 		l.setErr(err)
 
 		if l.err != nil {