From 3d51830ec7c363602f1f505a3270307b75fa744d Mon Sep 17 00:00:00 2001
From: falsycat <me@falsy.cat>
Date: Fri, 4 Oct 2019 00:00:00 +0000
Subject: [PATCH] [add] Implemented a part of parsing rules.

---
 sjscript/src/sjscript/parse.d | 105 ++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 sjscript/src/sjscript/parse.d

diff --git a/sjscript/src/sjscript/parse.d b/sjscript/src/sjscript/parse.d
new file mode 100644
index 0000000..42eb999
--- /dev/null
+++ b/sjscript/src/sjscript/parse.d
@@ -0,0 +1,105 @@
+/// License: MIT
+module sjscript.parse;
+
+import dast.parse;
+
+import sjscript.Expression,
+       sjscript.ParametersBlock,
+       sjscript.Token;
+
+///
+unittest {
+  import std;
+  import dast.tokenize : Tokenize;
+
+  enum src = q"EOS
+    framebuffer 0 {
+      a = 0;
+      b += 0;
+    }
+EOS";
+  try {
+    src.
+      Tokenize!TokenType.
+      filter!(x => x.type != TokenType.Whitespace).
+      chain([Token("", TokenType.End)]).
+      Parse().
+      each!writeln;
+  } catch (ParseException!Token e) {
+    "%s at %s".writefln(e.msg, e.token);
+  }
+}
+
+///
+ParametersBlock[] Parse(R)(R tokens) {
+  return dast.parse.Parse!Whole(tokens, cast(RuleSet) null).blocks;
+}
+
+private class RuleSet {
+ public:
+ @ParseRule:
+  static Whole ParseWhole(ParametersBlock[] blocks, @(TokenType.End) Token) {
+    return Whole(blocks);
+  }
+
+  static ParametersBlock[] ParseParametersBlockListFirstItem(ParametersBlock block) {
+    return [block];
+  }
+  static ParametersBlock[] ParseParametersBlockListFollowingItem(
+      ParametersBlock[] blocks, ParametersBlock block) {
+    return blocks ~ block;
+  }
+
+  static ParametersBlock ParseParametersBlock(
+      @(TokenType.Ident) Token target,
+      Period period,
+      @(TokenType.OpenBrace) Token,
+      Parameter[] params,
+      @(TokenType.CloseBrace) Token closebrace) {
+    return ParametersBlock(
+        target.text, period, params, CreateTokenPos(target, closebrace));
+  }
+
+  static Period ParsePeriod(@(TokenType.Number) Token) {  // TODO
+    return Period(0, 0);
+  }
+
+  static Parameter[] ParseParameterListFirstItem(Parameter param) {
+    return [param];
+  }
+  static Parameter[] ParseParameterListFollowingItem(
+      Parameter[] params, Parameter param) {
+    return params ~ param;
+  }
+
+  static Parameter ParseAssignParameter(
+      @(TokenType.Ident) Token ident,
+      @(TokenType.Assign) Token,
+      Expression expr,
+      @(TokenType.SemiColon) Token semicolon) {
+    return Parameter(
+        ident.text, ParameterType.Assign, expr, CreateTokenPos(ident, semicolon));
+  }
+  static Parameter ParseAddAssignParameter(
+      @(TokenType.Ident) Token ident,
+      @(TokenType.AddAssign) Token,
+      Expression expr,
+      @(TokenType.SemiColon) Token semicolon) {
+    return Parameter(
+        ident.text, ParameterType.AddAssign, expr, CreateTokenPos(ident, semicolon));
+  }
+
+  static Expression ParseExpression(@(TokenType.Number) Token) {  // TODO
+    return Expression();
+  }
+}
+
+private struct Whole {
+  ParametersBlock[] blocks;
+}
+
+private TokenPos CreateTokenPos(Token first, Token last) {
+  return TokenPos(
+      first.pos.stline, last.pos.edline,
+      first.pos.stchar, last.pos.edchar);
+}