10000 Add support for PEP 634 match statements · geddski/python@d370cbb · GitHub
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Add support for PEP 634 match statements
See https://peps.python.org/pep-0634/ FEATURE: Parse Python 3.10 match statements (PEP 634). Closes lezer-parser#10
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+81
-5
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3 files changed

+81
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‎src/python.grammar

Lines changed: 40 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,6 +10,7 @@
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xor @left,
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bitor @left,
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compare @left,
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as @left,
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and @left,
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or @left
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}
@@ -29,6 +30,41 @@ FunctionDefinition {
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ParamList { "(" commaSep<param>? ")" }
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MatchStatement {
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skw<"match"> "*"? expression MatchBody { ":" newline indent MatchClause+ (dedent | eof) }
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}
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MatchClause {
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skw<"case"> commaSep<pattern> Guard { kw<"if"> expression }? Body
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}
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pattern[@isGroup=Pattern] {
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CapturePattern { VariableName } |
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LiteralPattern |
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AsPattern { pattern !as kw<"as"> VariableName } |
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OrPattern { pattern (!or LogicOp{"|"} pattern)+ } |
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AttributePattern |
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SequencePattern |
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MappingPattern |
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StarPattern { "*" !prefix pattern } |
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ClassPattern { (VariableName | AttributePattern) PatternArgList }
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}
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AttributePattern { VariableName ("." PropertyName)+ }
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LiteralPattern {
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ArithOp{"-"}? Number (ArithOp{"+"|"-"} Number)? |
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String |
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kw<"None"> |
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@specialize[@name=Boolean]<identifier, "True" | "False">
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}
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PatternArgList { "(" commaSep<pattern | KeywordPattern { VariableName "=" pattern }> ")" }
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SequencePattern { "[" commaSep<pattern> "]" | "(" commaSep<pattern> ")" }
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MappingPattern { "{" commaSep<"**" pattern | (VariableName | LiteralPattern) ":" pattern> "}" }
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ClassDefinition { kw<"class"> VariableName ArgList? Body }
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param { VariableName TypeDef? (AssignOp{"="} test)? | "*" VariableName? | "**" VariableName | "/" }
@@ -78,7 +114,8 @@ compoundStatement {
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WithStatement { kw<"async">? kw<"with"> commaSep<test (kw<"as"> VariableName)?> Body } |
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FunctionDefinition |
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ClassDefinition |
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DecoratedStatement { Decorator+ (ClassDefinition | FunctionDefinition) }
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DecoratedStatement { Decorator+ (ClassDefinition | FunctionDefinition) } |
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MatchStatement
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}
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elseClause { kw<"else"> Body }
@@ -205,6 +242,8 @@ dottedName { VariableName ("." VariableName)* }
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kw<term> { @specialize[@name={term}]<identifier, term> }
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skw<term> { @extend[@name={term}]<identifier, term> }
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@skip {} {
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String {
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shortString |

‎src/tokens.js

Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -2,19 +2,21 @@ import {ExternalTokenizer, ContextTracker} from "@lezer/lr"
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import {
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newline as newlineToken, eof, newlineEmpty, newlineBracketed, indent, dedent, printKeyword,
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ParenthesizedExpression, TupleExpression, ComprehensionExpression,
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PatternArgList, SequencePattern, MappingPattern,
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ArrayExpression, ArrayComprehensionExpression, ArgList, ParamList, importList, subscript,
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DictionaryExpression, DictionaryComprehensionExpression, SetExpression, SetComprehensionExpression, FormatReplacement,
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ParenL, BraceL, BracketL
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} from "./parser.terms.js"
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const newline = 10, carriageReturn = 13, space = 32, tab = 9, hash = 35, parenOpen = 40, dot = 46
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const bracketed = [
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const bracketed = new Set([
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ParenthesizedExpression, TupleExpression, ComprehensionExpression, importList, ArgList, ParamList,
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ArrayExpression, ArrayComprehensionExpression, subscript,
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SetExpression, SetComprehensionExpression,
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DictionaryExpression, DictionaryComprehensionExpression, FormatReplacement
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]
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DictionaryExpression, DictionaryComprehensionExpression, FormatReplacement,
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SequencePattern, MappingPattern, PatternArgList
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])
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export const newlines = new ExternalTokenizer((input, stack) => {
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if (input.next < 0) {
@@ -71,7 +73,7 @@ function countIndent(space) {
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export const trackIndent = new ContextTracker({
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start: topIndent,
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reduce(context, term) {
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return context.depth < 0 && bracketed.indexOf(term) > -1 ? context.parent : context
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return context.depth < 0 && bracketed.has(term) ? context.parent : context
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},
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shift(context, term, stack, input) {
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if (term == indent) return new IndentLevel(context, countIndent(input.read(input.pos, stack.pos)))

‎test/statement.txt

Lines changed: 35 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -348,3 +348,38 @@ Script(ClassDefinition(class,VariableName,Body(
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FunctionDefinition(def,VariableName,ParamList(VariableName,VariableName),Body(
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AssignStatement(MemberExpression(VariableName,PropertyName),AssignOp,VariableName),
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AssignStatement(MemberExpression(VariableName,PropertyName),AssignOp,VariableName))))))
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# Parses match statements
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match foo:
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case 1:
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pass
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case Point("a", True) as z | a.b | {x: None, **y}:
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pass
359+
case [a, b, *rest] | (p, q):
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pass
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==>
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Script(MatchStatement(match,VariableName,MatchBody(
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MatchClause(case,
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LiteralPattern(Number),
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Body(PassStatement(pass))),
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MatchClause(case,
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OrPattern(
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AsPattern(
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ClassPattern(VariableName,PatternArgList(LiteralPattern(String),LiteralPattern(Boolean))),
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as,VariableName),
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LogicOp,
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AttributePattern(VariableName,PropertyName),
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LogicOp,
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MappingPattern(VariableName,LiteralPattern(None),CapturePattern(VariableName))),
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Body(PassStatement(pass))),
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MatchClause(case,
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OrPattern(SequencePattern(
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CapturePattern(VariableName),
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CapturePattern(VariableName),
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StarPattern(CapturePattern(VariableName))),
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LogicOp,
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SequencePattern(CapturePattern(VariableName),CapturePattern(VariableName))),
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Body(PassStatement(pass))))))

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