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basic: more parser wip

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minjaesong
2020-12-10 21:50:33 +09:00
parent bcec2b4536
commit 401bb47481
3 changed files with 107 additions and 27 deletions
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43
assets/tbas/parser_wip.js
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@@ -24,6 +24,8 @@ bF._parseStmt = function(lnum, tokens, states, recDepth) {
treeHead.astDepth = recDepth;
treeHead.astLnum = lnum;
// ## case for:
// "IF" , if_equation , "THEN" , stmt , ["ELSE" , stmt]
if ("IF" == headTkn && "lit" == headSta) {
// find nearest THEN and ELSE but also take parens into account
let thenPos = -1;
@@ -59,14 +61,43 @@ bF._parseStmt = function(lnum, tokens, states, recDepth) {
// "THEN" not found, raise error!
if (thenPos == -1) throw ParserError("IF without THEN in " + lnum);
// TODO gotta go home :)
treeHead.astValue = "IF";
treeHead.astType = "function";
treeHead.astLeaves[0] = bF._parseEquation(lnum,
tokens.slice(1, thenPos),
states.slice(1, thenPos),
recDepth + 1,
true // if_equation mode
);
treeHead.astLeaves[1] = bF._parseStmt(lnum,
tokens.slice(thenPos + 1, (elsePos != -1) ? elsePos : tokens.length),
states.slice(thenPos + 1, (elsePos != -1) ? elsePos : tokens.length),
recDepth + 1
);
if (elsePos != -1)
treeHead.astLeaves[2] = bF._parseStmt(lnum,
tokens.slice(elsePos + 1, tokens.length),
states.slice(elsePos + 1, tokens.length),
recDepth + 1
);
return treeHead;
}
// ## case for:
// ???
// TODO
}
/** Parses following EBNF rule:
* lit (* which is parsed by the tokeniser already *)
* @return: BasicAST
*/
bF._parseLit = function(lnum, tokens, states, recDepth) {
if (tokens.length > 1) throw ParserError();
let treeHead = new BasicAST();
treeHead.astDepth = recDepth;
treeHead.astLnum = lnum;
@@ -82,7 +113,7 @@ bF._parseLit = function(lnum, tokens, states, recDepth) {
}
// else, screw it
else {
throw lang.syntaxfehler(lnum, "TRAP_LITERALLY_LITERAL");
throw ParserError("TRAP_LITERALLY_LITERAL");
}
}
@@ -98,7 +129,7 @@ bF._parseLit = function(lnum, tokens, states, recDepth) {
* @return: BasicAST
*/
bF._EquationIllegalTokens = ["IF","THEN","ELSE","DEFUN","ON"];
bF._parseEquation = function(lnum, tokens, states, recDepth) {
bF._parseEquation = function(lnum, tokens, states, recDepth, ifMode) {
// scan for operators with highest precedence, use rightmost one if multiple were found
let topmostOp;
let topmostOpPrc = 0;
@@ -156,6 +187,10 @@ bF._parseEquation = function(lnum, tokens, states, recDepth) {
if (topmostOp !== undefined) {
if (_debugSyntaxAnalysis) serial.println("operator: "+topmostOp+", pos: "+operatorPos);
if (ifMode && topmostOp == "=") throw lang.syntaxfehler(lnum, "'=' used on IF, did you mean '=='?");
if (ifMode && topmostOp == ":") throw lang.syntaxfehler(lnum, "':' used on IF");
// this is the AST we're going to build up and return
// (other IF clauses don't use this)
let treeHead = new BasicAST();
@@ -188,7 +223,7 @@ bF._parseEquation = function(lnum, tokens, states, recDepth) {
// ## case for:
// lit
let headTkn = tokens[0].toUpperCase();
if (!bF._EquationIllegalTokens.includes(headTkn)) {
if (!bF._EquationIllegalTokens.includes(headTkn) && tokens.length == 1) {
return bF._parseLit(lnum, tokens, states, recDepth + 1);
}