From 244cc7ad6855696891cd8c72bfedb68c91fd1aaa Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 7 Jun 2023 20:03:39 +0100
Subject: Add parser for minimal functions

---
 .../java/org/shedlang/compiler/parser/Parser.java  | 49 ++++++++++++++++++++++
 .../org/shedlang/compiler/parser/TokenType.java    |  3 ++
 .../org/shedlang/compiler/parser/Tokeniser.java    |  4 ++
 3 files changed, 56 insertions(+)

(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 59850dc9..f76dfd78 100644
--- a/src/main/java/org/shedlang/compiler/parser/Parser.java
+++ b/src/main/java/org/shedlang/compiler/parser/Parser.java
@@ -7,6 +7,7 @@ import org.shedlang.compiler.tokeniser.UnexpectedTokenException;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 import java.util.function.BooleanSupplier;
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
@@ -80,6 +81,36 @@ public class Parser {
         return new UntypedExpressionStatementNode(expression, source);
     }
 
+    private static UntypedNamespaceStatementNode parseFunctionDefinition(TokenIterator<TokenType> tokens) {
+        var start = tokens.position();
+
+        tokens.skip(TokenType.KEYWORD_FUN);
+        var name = tokens.nextValue(TokenType.IDENTIFIER);
+
+        tokens.skip(TokenType.SYMBOL_PAREN_OPEN);
+        var params = parseParams(tokens);
+        tokens.skip(TokenType.SYMBOL_PAREN_CLOSE);
+
+        tokens.skip(TokenType.SYMBOL_THIN_ARROW);
+        var returnType = parseTopLevelTypeLevelExpression(tokens);
+
+        tokens.skip(TokenType.SYMBOL_BRACE_OPEN);
+        var body = List.<UntypedFunctionStatementNode>of();
+        tokens.skip(TokenType.SYMBOL_BRACE_CLOSE);
+
+        var end = tokens.position();
+        var source = start.to(end);
+
+        return new UntypedFunctionDefinitionNode(
+            name,
+            params,
+            Optional.empty(),
+            returnType,
+            body,
+            source
+        );
+    }
+
     static UntypedFunctionStatementNode parseFunctionStatement(TokenIterator<TokenType> tokens) {
         return parseExpressionStatement(tokens);
     }
@@ -102,6 +133,24 @@ public class Parser {
         return values;
     }
 
+    static UntypedNamespaceStatementNode parseNamespaceStatement(TokenIterator<TokenType> tokens) {
+        return switch (tokens.peek().tokenType()) {
+            case KEYWORD_FUN -> parseFunctionDefinition(tokens);
+
+            default ->
+                throw new UnexpectedTokenException("namespace statement", tokens.peek());
+        };
+    }
+
+    private static UntypedParamsNode parseParams(TokenIterator<TokenType> tokens) {
+        var start = tokens.position();
+
+        var end = tokens.position();
+        var source = start.to(end);
+
+        return new UntypedParamsNode(List.of(), List.of(), source);
+    }
+
     private static UntypedExpressionNode parsePrimaryExpression(TokenIterator<TokenType> tokens) {
         return switch (tokens.peek().tokenType()) {
 
diff --git a/src/main/java/org/shedlang/compiler/parser/TokenType.java b/src/main/java/org/shedlang/compiler/parser/TokenType.java
index 5a54f9a7..6df8e954 100644
--- a/src/main/java/org/shedlang/compiler/parser/TokenType.java
+++ b/src/main/java/org/shedlang/compiler/parser/TokenType.java
@@ -10,10 +10,13 @@ public enum TokenType {
     KEYWORD_FUN,
 
     SYMBOL_BANG,
+    SYMBOL_BRACE_OPEN,
+    SYMBOL_BRACE_CLOSE,
     SYMBOL_COMMA,
     SYMBOL_DOT,
     SYMBOL_EQUALS,
     SYMBOL_PAREN_OPEN,
     SYMBOL_PAREN_CLOSE,
     SYMBOL_SEMICOLON,
+    SYMBOL_THIN_ARROW,
 }
diff --git a/src/main/java/org/shedlang/compiler/parser/Tokeniser.java b/src/main/java/org/shedlang/compiler/parser/Tokeniser.java
index 33fe5716..32ddce50 100644
--- a/src/main/java/org/shedlang/compiler/parser/Tokeniser.java
+++ b/src/main/java/org/shedlang/compiler/parser/Tokeniser.java
@@ -19,7 +19,11 @@ public class Tokeniser {
     private static final RegexTokeniser<TokenType> tokeniser = new RegexTokeniser<>(
         TokenType.UNKNOWN,
         List.of(
+            RegexTokeniser.rule(TokenType.SYMBOL_THIN_ARROW, "->"),
+
             RegexTokeniser.rule(TokenType.SYMBOL_BANG, "!"),
+            RegexTokeniser.rule(TokenType.SYMBOL_BRACE_OPEN, "\\{"),
+            RegexTokeniser.rule(TokenType.SYMBOL_BRACE_CLOSE, "\\}"),
             RegexTokeniser.rule(TokenType.SYMBOL_COMMA, ","),
             RegexTokeniser.rule(TokenType.SYMBOL_DOT, "\\."),
             RegexTokeniser.rule(TokenType.SYMBOL_EQUALS, "="),
-- 
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