diff options
Diffstat (limited to 'compiler/jsgen.nim')
| -rw-r--r-- | compiler/jsgen.nim | 34 |
1 files changed, 27 insertions, 7 deletions
diff --git a/compiler/jsgen.nim b/compiler/jsgen.nim index 96d8b3d11..dfe498e47 100644 --- a/compiler/jsgen.nim +++ b/compiler/jsgen.nim @@ -10,6 +10,25 @@ # This is the JavaScript code generator. # Soon also a Luajit code generator. ;-) +discard """ +The JS code generator contains only 2 tricks: + +Trick 1 +------- +Some locations (for example 'var int') require "fat pointers" (``etyBaseIndex``) +which are pairs (array, index). The derefence operation is then 'array[index]'. +Check ``mapType`` for the details. + +Trick 2 +------- +It is preferable to generate '||' and '&&' if possible since that is more +idiomatic and hence should be friendlier for the JS JIT implementation. However +code like ``foo and (let bar = baz())`` cannot be translated this way. Instead +the expressions need to be transformed into statements. ``isSimpleExpr`` +implements the required case distinction. +""" + + import ast, astalgo, strutils, hashes, trees, platform, magicsys, extccomp, options, nversion, nimsets, msgs, crc, bitsets, idents, lists, types, os, @@ -833,8 +852,8 @@ proc genSwap(p: PProc, n: PNode) = "local $1 = $2; $2 = $3; $3 = $1;$n", [ tmp, a.address, b.address]) tmp = tmp2 - appf(p.body, "var $1 = $2; $2 = $3; $3 = $1" | - "local $1 = $2; $2 = $3; $3 = $1", [tmp, a.res, b.res]) + appf(p.body, "var $1 = $2; $2 = $3; $3 = $1;" | + "local $1 = $2; $2 = $3; $3 = $1;", [tmp, a.res, b.res]) proc getFieldPosition(f: PNode): int = case f.kind @@ -881,14 +900,15 @@ proc genArrayAddr(p: PProc, n: PNode, r: var TCompRes) = a, b: TCompRes first: BiggestInt r.typ = etyBaseIndex - gen(p, n.sons[0], a) - gen(p, n.sons[1], b) + let m = if n.kind == nkHiddenAddr: n.sons[0] else: n + gen(p, m.sons[0], a) + gen(p, m.sons[1], b) internalAssert a.typ != etyBaseIndex and b.typ != etyBaseIndex r.address = a.res - var typ = skipTypes(n.sons[0].typ, abstractPtrs) + var typ = skipTypes(m.sons[0].typ, abstractPtrs) if typ.kind in {tyArray, tyArrayConstr}: first = firstOrd(typ.sons[0]) else: first = 0 - if optBoundsCheck in p.options and not isConstExpr(n.sons[1]): + if optBoundsCheck in p.options and not isConstExpr(m.sons[1]): useMagic(p, "chckIndx") r.res = ropef("chckIndx($1, $2, $3.length)-$2", [b.res, toRope(first), a.res]) @@ -1351,7 +1371,7 @@ proc genMagic(p: PProc, n: PNode, r: var TCompRes) = of mEcho: genEcho(p, n, r) of mSlurp, mStaticExec: localError(n.info, errXMustBeCompileTime, n.sons[0].sym.name.s) - of mCopyStr: binaryExpr(p, n, r, "", "($1.slice($2,-1))") + of mCopyStr: binaryExpr(p, n, r, "", "($1.slice($2))") of mCopyStrLast: ternaryExpr(p, n, r, "", "($1.slice($2, ($3)+1).concat(0))") of mNewString: unaryExpr(p, n, r, "mnewString", "mnewString($1)") of mNewStringOfCap: unaryExpr(p, n, r, "mnewString", "mnewString(0)") |