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asm-llvm: Allow (almost) arbitrary parenthesization of expressions.
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Still not supported: the ~~ operator and arbitrary parenthesization of
call sites (ie, plus coercion).
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@cscott
cscott committed Jun 10, 2013
1 parent 3bd4932 commit 5b4d9b9
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Showing 3 changed files with 201 additions and 52 deletions.
162 changes: 111 additions & 51 deletions asm-llvm.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1659,6 +1659,34 @@ define([], function asm_llvm() {
} else { next(); }
};

// It's sometimes handle to have a no-op function handy.
var noop = function() {};

// Eat up any left parens, returning a function to eat a
// corresponding number of right parens.
var parenStart = function() {
var numParens = 0;
while (eat(_parenL)) {
numParens += 1;
}
// optimize the common no-extra-parentheses case.
return (numParens===0) ? noop : function(onlySome) {
while (numParens) {
if (onlySome && tokType!==_parenR) { return; }
expect(_parenR);
numParens -= 1;
}
};
};

// Allow parentheses to be wrapped around the given parser function.
var withParens = function(f) {
var parenEnd = parenStart();
var v = f();
parenEnd();
return v;
};

// Restore old token position, prior to reparsing.
// This lets us implement >1 token lookahead, which is needed
// in a few places in the grammar (search for uses of backtrack()
Expand Down Expand Up @@ -1758,11 +1786,20 @@ define([], function asm_llvm() {
return module.env.lookup(id);
};

// Parse a numeric literal 0 (used for type annotations).
var parseLiteralZero = function() {
if (tokType !== _num || tokVal !== 0) {
raise(tokStart, "expected 0");
}
next();
};

// Parse a numeric literal, returning a type and a value.
var parseNumericLiteral = function() {
var numStart = tokStart;
var parenClose = noop;
var negate = (tokType===_plusmin && tokVal==='-');
if (negate) { next(); }
if (negate) { next(); parenClose = parenStart(); }
var result = ConstantBinding.New(Types.Double, tokVal);
if (tokType === _num) {
result.setIntType();
Expand All @@ -1772,7 +1809,7 @@ define([], function asm_llvm() {
} else if (tokType !== _dotnum) {
raise(numStart, "expected a numeric literal");
}
next();
next(); parenClose();
if (negate) { result.negate(); }
return result;
};
Expand Down Expand Up @@ -2340,7 +2377,7 @@ define([], function asm_llvm() {
next();
if (isCase) {
startPos = tokStart;
cur.test = parseNumericLiteral();
cur.test = withParens(parseNumericLiteral);
typecheck(cur.test.type, Types.Signed,
"switch case", startPos);
if (seen[cur.test.value]) {
Expand Down Expand Up @@ -2452,45 +2489,52 @@ define([], function asm_llvm() {
// ### Module-internal function parsing

// Parse a list of parameter type coercions.
// Note that we can't always tell these apart from body statements;
// we might have to backtrack.
var parseParameterTypeCoercions = function() {
var func = module.func;
var ptPos;
// Restore old token position before returning.
var bail = function() { return backtrack(ptPos); };
while (tokType === _name) {
// Save position of this token before starting to parse!
ptPos = tokStart;
// There will always be exactly as many of these as there are
// formal parameters.
var parseParameterTypeCoercions = function(numFormals) {
var func = module.func, startPos, parenClose, moreParen, ty;
while (numFormals) {
numFormals -= 1;
parenClose = parenStart();
startPos = tokStart;
var x = parseIdent();
parenClose('some');

var binding = func.env.lookup(x);
if (binding===null || binding.type!==Types.ForwardReference) {
return bail(); // not a parameter name, or already coerced
if (binding===null) {
raise(startPos, "expected parameter name");
} else if (binding.type!==Types.ForwardReference) {
raise(startPos, "duplicate parameter coercion");
}
if (tokType === _eq) { next(); } else { return bail(); }
expect(_eq);
moreParen = parenStart();
if (tokType === _name && tokVal === x) {
// This is an `int` type annotation.
next();
ty = Types.Int;
next(); moreParen('some');
if (!(tokType === _bin3 && tokVal === '|')) {
return bail();
} else { next(); }
if (!(tokType === _num && tokVal === 0)) {
return bail();
} else { next(); }
if (!(tokType === _semi)) { return bail(); }
binding.type = mergeTypes(binding.type, Types.Int, ptPos);
raise(tokStart, "expected | for int type annotation");
}
next();
withParens(parseLiteralZero);
} else if (tokType === _plusmin && tokVal==='+') {
// This is a `double` type annotation.
ty = Types.Double;
next();
if (tokType === _name && tokVal === x) {
next();
} else { return bail(); }
if (!(tokType === _semi)) { return bail(); }
binding.type=mergeTypes(binding.type, Types.Double, ptPos);
withParens(function() {
if (tokType === _name && tokVal === x) {
next();
} else {
raise(tokStart, "expected '"+x+"'");
}
});
} else {
return bail();
raise(tokStart, "expected int or double coercion");
}
expect(_semi);
binding.type = mergeTypes(binding.type, ty, startPos);
moreParen();
parenClose();
semicolon();
}
};

Expand All @@ -2503,7 +2547,7 @@ define([], function asm_llvm() {
var yPos = tokStart;
var y = parseIdent();
expect(_eq);
var n = parseNumericLiteral();
var n = withParens(parseNumericLiteral);
var ty = (n.type===Types.Double) ? Types.Double : Types.Int;
func.env.bind(y, LocalBinding.New(ty), yPos);
if (!eat(_comma)) { break; }
Expand Down Expand Up @@ -2538,7 +2582,7 @@ define([], function asm_llvm() {

// Parse the parameter type coercion statements, then
// verify that all the parameters were coerced to a type.
parseParameterTypeCoercions();
parseParameterTypeCoercions(func.params.length);
func.params.forEach(function(param) {
if (func.env.lookup(param).type===Types.ForwardReference) {
raise(fPos, "No parameter type annotation found for '" +
Expand Down Expand Up @@ -2583,22 +2627,23 @@ define([], function asm_llvm() {

// Parse a variable statement within a module.
var parseModuleVariableStatement = function() {
var x, y, ty, startPos, yPos;
var x, y, ty, startPos, yPos, parenClose, moreParen;
expect(_var);
// Allow comma-separated var expressions.
// (See https://github.com/dherman/asm.js/issues/63 .)
while (true) {
startPos = tokStart;
x = parseIdent();
expect(_eq);
parenClose = parenStart();
// There are five types of variable statements:
if (tokType === _bracketL) {
// 1\. A function table. (Only allowed at end of module.)
yPos = tokStart; next();
var table = [], lastType;
while (!eat(_bracketR)) {
if (table.length > 0) { expect(_comma); }
y = parseIdent();
y = withParens(parseIdent);
var b = module.env.lookup(y);
/* validate consistent types of named functions */
if (!b) { raise(lastStart, "Unknown function '"+y+"'");}
Expand Down Expand Up @@ -2645,11 +2690,12 @@ define([], function asm_llvm() {
module.env.bind(x, GlobalBinding.New(ty, true), startPos);
} else if (tokType === _name && tokVal === module.stdlib) {
// 3\. A standard library import.
next(); expect(_dot);
next(); parenClose('some'); expect(_dot);
yPos = tokStart;
y = parseIdent();
if (y==='Math') {
expect(_dot); y += '.' + parseIdent();
parenClose('some'); expect(_dot);
y += '.' + parseIdent();
}
ty = Types.stdlib[y];
if (!ty) { raise(yPos, "Unknown library import"); }
Expand All @@ -2658,16 +2704,18 @@ define([], function asm_llvm() {
(tokType === _name && tokVal === module.foreign)) {
// 4\. A foreign import.
var sawPlus = false, sawBar = false;
if (tokType===_plusmin) { next(); sawPlus = true; }
expectName(module.foreign, "<foreign>"); expect(_dot);
if (tokType===_plusmin) {
next(); sawPlus = true; moreParen = parenStart();
} else { moreParen = parenClose; }
expectName(module.foreign, "<foreign>");
moreParen('some'); expect(_dot);
y = parseIdent();
moreParen('some');
if (tokType === _bin3 && tokVal ==='|' && !sawPlus) {
next(); sawBar = true;
if (tokType !== _num || tokVal !== 0) {
raise(tokStart, "expected 0");
}
next();
withParens(parseLiteralZero);
}
moreParen();
ty = sawPlus ? Types.Double : sawBar ? Types.Int :
Types.Function;
// Foreign imports are mutable iff they are not
Expand All @@ -2677,7 +2725,10 @@ define([], function asm_llvm() {
module.env.bind(x, GlobalBinding.New(ty, mut), startPos);
} else if (tokType === _new) {
// 5\. A global heap view.
next(); expectName(module.stdlib, "<stdlib>"); expect(_dot);
next();
moreParen = parenStart();
expectName(module.stdlib, "<stdlib>");
moreParen('some'); expect(_dot);
yPos = tokStart;
var view = parseIdent();
if (view === 'Int8Array') { ty = Types.IntArray(8); }
Expand All @@ -2689,11 +2740,15 @@ define([], function asm_llvm() {
else if (view === 'Float32Array') {ty=Types.FloatArray(32);}
else if (view === 'Float64Array') {ty=Types.FloatArray(64);}
else { raise(yPos, "unknown ArrayBufferView type"); }
moreParen();
expect(_parenL);
moreParen = parenStart();
expectName(module.heap, "<heap>");
moreParen();
expect(_parenR);
module.env.bind(x, GlobalBinding.New(ty, false), startPos);
} else { unexpected(); }
parenClose();
if (!eat(_comma)) { break; }
}
semicolon();
Expand All @@ -2715,7 +2770,9 @@ define([], function asm_llvm() {

// Parse the module export declaration (return statement).
var parseModuleExportDeclaration = function() {
var parenClose;
expect(_return);
parenClose = parenStart();
var exports = module.exports = Object.create(null), first = true;
var fStart = tokStart;
var check = function(f) {
Expand All @@ -2732,16 +2789,17 @@ define([], function asm_llvm() {
var x = parseIdent();
expect(_colon);
fStart = tokStart;
var f = parseIdent();
var f = withParens(parseIdent);
exports[x] = check(f);
while (!eat(_braceR)) {
expect(_comma);
x = parseIdent();
expect(_colon);
f = parseIdent();
f = withParens(parseIdent);
exports[x] = check(f);
}
}
parenClose();
semicolon();
};

Expand Down Expand Up @@ -2783,11 +2841,13 @@ define([], function asm_llvm() {
}
expect(_braceL);
// Check for "use asm".
if (tokType !== _string ||
tokVal !== "use asm") {
raise(tokStart, "Expected to see 'use asm'");
}
next();
withParens(function() {
if (tokType !== _string ||
tokVal !== "use asm") {
raise(tokStart, "Expected to see 'use asm'");
}
next();
});
semicolon();

// Parse the body of the module. Note that
Expand Down
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