diff options
Diffstat (limited to 'src/interp/lexing.boot')
| -rw-r--r-- | src/interp/lexing.boot | 60 |
1 files changed, 59 insertions, 1 deletions
diff --git a/src/interp/lexing.boot b/src/interp/lexing.boot index 506e22c6..d26ef72d 100644 --- a/src/interp/lexing.boot +++ b/src/interp/lexing.boot @@ -71,7 +71,7 @@ stackClear! st == stackStore(st) := nil stackSize(st) := 0 stackTop(st) := nil - stackUpdate?(st) := false + stackUpdated?(st) := false stackPush!(x,st) == stackStore(st) := [x,:stackStore st] @@ -86,3 +86,61 @@ stackPop! st == if stackStore st ~= nil then stackTop(st) := first stackStore st y + + +--% +--% Parsing reduction stack +--% +--% Abstractly; +--% structure Reduction == Record(rule: RuleName, value: ParseTree) +--% +makeReduction(p == nil,v == nil) == + [p,v] + +macro reductionRule r == + first r + +macro reductionValue r == + second r + +++ stack of results of reduced productions +$reduceStack := makeStack() + +pushReduction(rn,pt) == + stackPush!(makeReduction(rn,pt),$reduceStack) + +popReduction() == + stackPop! $reduceStack + +reduceStackClear() == + stackClear! $reduceStack + +popStack1() == + reductionValue popReduction() + +popStack2() == + r1 := popReduction() + r2 := popReduction() + stackPush!(r1,$reduceStack) + reductionValue r2 + +popStack3() == + r1 := popReduction() + r2 := popReduction() + r3 := popReduction() + stackPush!(r2,$reduceStack) + stackPush!(r1,$reduceStack) + reductionValue r3 + +popStack4() == + r1 := popReduction() + r2 := popReduction() + r3 := popReduction() + r4 := popReduction() + stackPush!(r3,$reduceStack) + stackPush!(r2,$reduceStack) + stackPush!(r1,$reduceStack) + reductionValue r4 + +nthStack n == + reductionValue stackStore($reduceStack).(n - 1) |