From 838283c70654d5eb31a6a488e2719888f784fb83 Mon Sep 17 00:00:00 2001
From: Allen Webster <yoyo4thdimention@gmail.com>
Date: Sat, 9 Oct 2021 20:14:07 -0700
Subject: [PATCH] [examples] start setting up expression parser intro

---
 examples/expr/expr_intro.c     | 92 ++++++++++++++++++++++++++++++++++
 examples/expr/expr_intro.mdesk | 14 ++++++
 source/md.h                    |  6 ++-
 3 files changed, 111 insertions(+), 1 deletion(-)
 create mode 100644 examples/expr/expr_intro.c
 create mode 100644 examples/expr/expr_intro.mdesk

diff --git a/examples/expr/expr_intro.c b/examples/expr/expr_intro.c
new file mode 100644
index 0000000..70b33af
--- /dev/null
+++ b/examples/expr/expr_intro.c
@@ -0,0 +1,92 @@
+/* 
+** Example: expressions intro
+**
+** TODO
+**
+*/
+
+//~ includes and globals //////////////////////////////////////////////////////
+
+#include "md.h"
+#include "md.c"
+
+static MD_Arena *arena = 0;
+
+//~ expression setup and helpers //////////////////////////////////////////////
+
+void
+print_expression(FILE *out, MD_Expr *expr)
+{
+    // TODO(allen): finish
+}
+
+
+//~ main //////////////////////////////////////////////////////////////////////
+
+int main(int argc, char **argv)
+{
+    // setup the global arena
+    arena = MD_ArenaAlloc();
+    
+    // parse all files passed to the command line
+    MD_Node *list = MD_MakeList(arena);
+    for (int i = 1; i < argc; i += 1)
+    {
+        
+        // parse the file
+        MD_String8 file_name = MD_S8CString(argv[i]);
+        MD_ParseResult parse_result = MD_ParseWholeFile(arena, file_name);
+        
+        // print metadesk errors
+        for (MD_Message *message = parse_result.errors.first;
+             message != 0;
+             message = message->next)
+        {
+            MD_CodeLoc code_loc = MD_CodeLocFromNode(message->node);
+            MD_PrintMessage(stdout, code_loc, message->kind, message->string);
+        }
+        
+        // save to parse results list
+        if (parse_result.errors.max_message_kind < MD_MessageKind_Error)
+        {
+            MD_PushNewReference(arena, list, parse_result.node);
+        }
+    }
+    
+    // setup the expression system
+    MD_ExprOprTable table = {0};
+    {
+        MD_ExprOprList list = {0};
+        
+        MD_ExprOprPush(arena, &list, MD_ExprOprKind_Binary, 1, MD_S8Lit("+"), OpAdd, 0);
+        MD_ExprOprPush(arena, &list, MD_ExprOprKind_Binary, 2, MD_S8Lit("*"), OpMul, 0);
+        
+        table = MD_ExprBakeOperatorTableFromList(arena, &list);
+    }
+    
+    // print the verbose parse results
+    for (MD_EachNode(root_it, list->first_child))
+    {
+        MD_Node *root = MD_ResolveNodeFromReference(root_it);
+        for (MD_EachNode(node, root->first_child))
+        {
+            MD_ExprParseResult parse = MD_ExprParse(arena, &table, node->first_child, MD_NilNode());
+            
+            // print errors
+            for (MD_Message *message = parse.errors.first;
+                 message != 0;
+                 message = message->next)
+            {
+                MD_CodeLoc code_loc = MD_CodeLocFromNode(message->node);
+                MD_PrintMessage(stdout, code_loc, message->kind, message->string);
+            }
+            
+            // print the expression
+            fprintf(stdout, "%s = ");
+            print_expression(stdout, parse.expr);
+            fprintf(stdout, ";\n");
+        }
+    }
+    
+    return 0;
+}
diff --git a/examples/expr/expr_intro.mdesk b/examples/expr/expr_intro.mdesk
new file mode 100644
index 0000000..90cc1fc
--- /dev/null
+++ b/examples/expr/expr_intro.mdesk
@@ -0,0 +1,14 @@
+/*
+** Example: expressions intro
+** 
+** TODO
+*/
+
+a: 1;
+b: 2;
+c: 3;
+
+w: 100;
+x: a*w + b;
+y: b*w + c;
+z: c*w + a;
diff --git a/source/md.h b/source/md.h
index 970eb32..5c839a6 100644
--- a/source/md.h
+++ b/source/md.h
@@ -727,6 +727,7 @@ typedef struct MD_MessageList MD_MessageList;
 struct MD_MessageList
 {
     MD_MessageKind max_message_kind;
+    // TODO(allen): rename
     MD_u64 node_count;
     MD_Message *first;
     MD_Message *last;
@@ -780,7 +781,8 @@ struct MD_ExprOprList
 typedef struct MD_ExprOprTable MD_ExprOprTable;
 struct MD_ExprOprTable
 {
-    MD_ExprOprList table[MD_ExprOprKind_COUNT]; // TODO(mal): Hash?
+    // TODO(mal): @upgrade_potential Hash?
+    MD_ExprOprList table[MD_ExprOprKind_COUNT];
     MD_MessageList errors;
 };
 
@@ -791,6 +793,7 @@ struct MD_Expr
     struct MD_Expr *left;
     struct MD_Expr *right;
     MD_b32 is_op;
+    // TODO(allen): this should be MD_ExprOpr*
     MD_u32 op_id;
     void *op_ptr;
     MD_Node *md_node;
@@ -818,6 +821,7 @@ struct MD_ExprParseCtx
     } accel;
 #undef MD_POSTFIX_SETLIKE_OP_COUNT
     
+    // TODO(allen): different message list type here
     MD_MessageList errors;
 };