From f497e7f884856ca91f3697886db559af070a92ba Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 5 Jul 2023 21:30:56 +0100
Subject: Parse function definition params

---
 .../java/org/shedlang/compiler/parser/Parser.java  | 35 +++++++++++++++++++---
 .../PositionalParamAfterNamedParamError.java       | 11 +++++++
 .../org/shedlang/compiler/parser/TokenType.java    |  1 +
 .../org/shedlang/compiler/parser/Tokeniser.java    |  1 +
 4 files changed, 44 insertions(+), 4 deletions(-)
 create mode 100644 src/main/java/org/shedlang/compiler/parser/PositionalParamAfterNamedParamError.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/parser/Parser.java b/src/main/java/org/shedlang/compiler/parser/Parser.java
index 69d02075..b1794c6c 100644
--- a/src/main/java/org/shedlang/compiler/parser/Parser.java
+++ b/src/main/java/org/shedlang/compiler/parser/Parser.java
@@ -178,12 +178,39 @@ public class Parser {
     }
 
     private static UntypedParamsNode parseParams(TokenIterator<TokenType> tokens) {
-        var start = tokens.position();
+        var paramsStart = tokens.position();
 
-        var end = tokens.position();
-        var source = start.to(end);
+        var positional = new ArrayList<UntypedParamNode>();
+        var named = new ArrayList<UntypedParamNode>();
+
+        parseMany(
+            () -> tokens.isNext(TokenType.SYMBOL_PAREN_CLOSE),
+            () -> {
+                var isNamed = tokens.trySkip(TokenType.SYMBOL_DOT);
+
+                var paramStart = tokens.position();
+
+                var name = tokens.nextValue(TokenType.IDENTIFIER);
+                tokens.skip(TokenType.SYMBOL_COLON);
+                var type = parseTopLevelTypeLevelExpression(tokens);
+                if (!isNamed && !named.isEmpty()) {
+                    throw new PositionalParamAfterNamedParamError(type.source());
+                }
+
+                var paramEnd = tokens.position();
+                var paramSource = paramStart.to(paramEnd);
+
+                (isNamed ? named : positional).add(new UntypedParamNode(name, type, paramSource));
+
+                return null;
+            },
+            () -> tokens.trySkip(TokenType.SYMBOL_COMMA)
+        );
+
+        var paramsEnd = tokens.position();
+        var paramsSource = paramsStart.to(paramsEnd);
 
-        return new UntypedParamsNode(List.of(), List.of(), source);
+        return new UntypedParamsNode(positional, named, paramsSource);
     }
 
     private static UntypedExpressionNode parsePrimaryExpression(TokenIterator<TokenType> tokens) {
diff --git a/src/main/java/org/shedlang/compiler/parser/PositionalParamAfterNamedParamError.java b/src/main/java/org/shedlang/compiler/parser/PositionalParamAfterNamedParamError.java
new file mode 100644
index 00000000..e32865f6
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/parser/PositionalParamAfterNamedParamError.java
@@ -0,0 +1,11 @@
+package org.shedlang.compiler.parser;
+
+import org.shedlang.compiler.errors.SourceError;
+import org.shedlang.compiler.sources.Source;
+
+public class PositionalParamAfterNamedParamError extends SourceError {
+    public PositionalParamAfterNamedParamError(Source source) {
+        super("Positional param cannot follow named param", source);
+    }
+}
+
diff --git a/src/main/java/org/shedlang/compiler/parser/TokenType.java b/src/main/java/org/shedlang/compiler/parser/TokenType.java
index 21e830f0..2972ce59 100644
--- a/src/main/java/org/shedlang/compiler/parser/TokenType.java
+++ b/src/main/java/org/shedlang/compiler/parser/TokenType.java
@@ -16,6 +16,7 @@ public enum TokenType {
     SYMBOL_BANG,
     SYMBOL_BRACE_OPEN,
     SYMBOL_BRACE_CLOSE,
+    SYMBOL_COLON,
     SYMBOL_COMMA,
     SYMBOL_DOT,
     SYMBOL_EQUALS,
diff --git a/src/main/java/org/shedlang/compiler/parser/Tokeniser.java b/src/main/java/org/shedlang/compiler/parser/Tokeniser.java
index 131462f7..4c06a20a 100644
--- a/src/main/java/org/shedlang/compiler/parser/Tokeniser.java
+++ b/src/main/java/org/shedlang/compiler/parser/Tokeniser.java
@@ -27,6 +27,7 @@ public class Tokeniser {
             RegexTokeniser.rule(TokenType.SYMBOL_BANG, "!"),
             RegexTokeniser.rule(TokenType.SYMBOL_BRACE_OPEN, "\\{"),
             RegexTokeniser.rule(TokenType.SYMBOL_BRACE_CLOSE, "\\}"),
+            RegexTokeniser.rule(TokenType.SYMBOL_COLON, ":"),
             RegexTokeniser.rule(TokenType.SYMBOL_COMMA, ","),
             RegexTokeniser.rule(TokenType.SYMBOL_DOT, "\\."),
             RegexTokeniser.rule(TokenType.SYMBOL_EQUALS, "="),
-- 
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