[PATCH 031/188] starting wat parser

From dac6a21cff27a4cdd55c55688abe61af74780540 Mon Sep 17 00:00:00 2001
From: Dmitry Boyarintsev <skalogryz.lists@gmail.com>
Date: Tue, 19 Nov 2019 20:24:00 -0500

git-svn-id: branches/wasm@46027 -

utils/wasmbin/watparser.pas

@@ -1,7 +1,115 @@
 unit watparser;
 
-interface 
+{$mode delphi}{$H+}
+
+interface
+
+uses
+  SysUtils, Classes, parseutils;
+
+type
+  TWatEntity = (weNone, weError,
+     weIdent, weString, weNumber, weSymbol, weOpenBrace, weCloseBrace);
+
+  { TWatParser }
+
+  TWatParser = class(TObject)
+  protected
+    procedure DoComment(const cmt: string);
+    function CommentIsSymbol(const cmt: string): Boolean;
+  public
+    buf : string;
+    idx : integer;
+
+    ofs : integer;
+    entity : TWatEntity;
+    resText : string;
+    procedure SetSource(const abuf: string);
+    function Next: Boolean;
+  end;
+
+const
+  SymbolChars : TCharSet = ['(',')'];
+  AlphaNumCharsUnd : TCharSet = AlphaNumChars + ['_','$'];
 
 implementation
 
-end.
+{ TWatParser }
+
+procedure TWatParser.DoComment(const cmt: string);
+begin
+
+end;
+
+function TWatParser.CommentIsSymbol(const cmt: string): Boolean;
+begin
+  Result := false;
+end;
+
+procedure TWatParser.SetSource(const abuf: string);
+begin
+  buf:=abuf;
+  idx:=1;
+end;
+
+function TWatParser.Next: Boolean;
+var
+  has2chars: Boolean;
+  cmt : string;
+  done: boolean;
+  j: integer;
+begin
+  Result := idx<=length(buf);
+  if not Result then Exit;
+
+  done:=false;
+  resText:='';
+  while not done do begin
+    ScanWhile(buf, idx, WhiteSpaceChars);
+    Result := idx<=length(buf);
+    if not Result then Exit;
+    j:=idx;
+    has2chars := idx<length(buf);
+    if has2chars then begin
+      if (buf[idx]=';') and (buf[idx+1]=';') then begin
+        // comment until the end of the line
+        cmt := ScanTo(buf, idx, EoLnChars);
+        ScanWhile(buf, idx, EoLnChars);
+      end else if (buf[idx]='(') and (buf[idx+1]=';') then
+        // comment until the ;)
+        cmt := ScanToSubstr(buf, idx, ';)');
+
+      if CommentIsSymbol(cmt) then begin
+        entity:=weSymbol;
+        done:=true;
+      end else
+        DoComment(cmt);
+    end;
+
+    if not done then begin
+      done:=true;
+      if buf[idx] = '(' then begin
+        entity:=weOpenBrace;
+        inc(idx);
+      end else if buf[idx]=')' then begin
+        entity:=weCloseBrace;
+        inc(idx);
+      end else if buf[idx] in AlphabetChars then begin
+        entity:=weIdent;
+        resText:=ScanWhile(buf, idx, AlphaNumCharsUnd);
+      end else if buf[idx] in NumericChars then begin
+        entity:=weNumber;
+        resText:=ScanWhile(buf, idx, NumericChars);
+      end else begin
+        entity:=weError;
+        inc(idx);
+        done:=true;
+      end;
+    end;
+  end;
+
+  if resText='' then
+    resText := Copy(buf, j, idx-j);
+end;
+
+end.