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2023-08-10Move the trait `Forest` to the crate "forest".JSDurand
The purpose of this change is to share this trait with other crates, such as the forth-coming "semiring" crate that will be responsible for handling some simple semiring operations as well as the querying, in my plans.
2023-08-09Fix a bug of using incorrect forest nodes to plant.JSDurand
Previously some incorrect forest nodes will be used for planting new nodes. I cannot fix the root cause of their presence in the chain-rule machine. But I can ignore them when they are encountered. Of course I would like to really prevent them from existing, but still cannot figure out how.
2023-08-04chain/default: Add funtion `print_current`JSDurand
* chain/src/default.rs: This is useful for debugging the chain-rule machine.
2023-08-01Fix some bugsJSDurand
Some bugs are fixed: 1. If a non-terminal expansion can be reduced immediately, previously an extra node would be created that had no parents. Now this strange behaviour is corrected. 2. When performing reductions, a leaf non-terminal node would previously be regarded as completed. Now we will first try to complete that node, and then determine if the completion is successful, and finally determine the completedness according to the result. Of course some more tests are still pending, before I can confirm that no more bugs lurk around.
2023-07-30chain/default.rs: Minor adjustment and add a planJSDurand
Adjust the codes slightly. Also add a plan to implement the context-free memoization.
2023-07-21chain/default: Remove the annoying node whenever plausible.JSDurand
The chain-rule machine needs a place-holder node at the beginning. But afterwards that node is pure annoyance and disturbs the functioning of the machine. Consequently I removed that node whenever the right time comes. This seems to fix some other bugs. It is reasonable: the presence of that bogus node is just noise to the machine and error-prone.
2023-07-18Fix a bug of unnecessarily cloning nodes.JSDurand
* chain/src/item/default/splone.rs: Previously when we split nodes, we always clone the parent if the labels differ. This turns out to be incorrect if the new label is open whereas the old label is closed. In that case, the old parent should not contain the new node as a child, as a closed node should not contain an open node. I am not yet entirely sure this fix is correct, so more test await us.
2023-07-16Fix the bug of forgetting to check cloned nodes.JSDurand
In the process of splitting, cloning, and planting the forest, I forgot to check whether some cloned node of the node inquestion satisfy the condition. This used to cause forests that violate some fundamental assumptions. Now this is supposed to be fixed, but more tests await us.
2023-07-08Finished the Emacs binding.JSDurand
Now the binding part is finished. What remains is a bug encountered when planting a fragment to the forest which intersects a packed node, which would lead to invalid forests. This will also cause problem when planting a packed fragment, but until now my testing grammars do not produce packed fragments, so this problem is not encountered yet. I am still figuring out efficient ways to solve this problem.
2023-06-18fixed the bugs of node duplications and left-open nodesJSDurand
There were two main issues in the previous version. One is that there are lots of duplications of nodes when manipulating the forest. This does not mean that labels repeat: by the use of the data type this cannot happen. What happened is that there were cloned nodes whose children are exactly equal. In this case there is no need to clone that node in the first place. This is now fixed by checking carefully before cloning, so that we do not clone unnecessary nodes. The other issue, which is perhaps more important, is that there are nodes which are not closed. This means that when there should be a reuction of grammar rules, the forest does not mark the corresponding node as already reduced. The incorrect forests thus caused is hard to fix: I tried several different approaches to fix it afterwards, but all to no avail. I also tried to record enough information to fix these nodes during the manipulations. It turned out that recording nodes is a dead end, as I cannot properly syncronize the information in the forest and the information in the chain-rule machine. Any inconsistencies will result in incorrect operations later on. The approach I finally adapt is to perform every possible reduction at each step. This might lead to some more nodes than what we need. But those are technically expected to be there after all, and it is easy to filter them out, so it is fine, from my point of view at the moment. Therefore, what remains is to filter those nodes out and connect it to the holy Emacs. :D
2023-06-02Fix a bug of duplication from planting after sploingJSDurand
I should have staged and committed these changes separately, but I am too lazy to deal with that. The main changes in this commit are that I added the derive macro that automates the delegation of the Graph trait. This saves a lot of boiler-plate codes. The second main change, perhaps the most important one, is that I found and tried to fix a bug that caused duplication of nodes. The bug arises from splitting or cloning a node multiple times, and immediately planting the same fragment under the new "sploned" node. That is, when we try to splone the node again, we found that we need to splone, because the node that was created by the same sploning process now has a different label because of the planting of the fragment. Then after the sploning, we plant the fragment again. This makes the newly sploned node have the same label (except for the clone index) and the same children as the node that was sploned and planted in the previous rounds. The fix is to check for the existence of a node that has the same set of children as the about-to-be-sploned node, except for the last one, which contains the about-to-be-planted fragment as a prefix. If that is the case, treat it as an already existing node, so that we do not have to splone the node again. This is consistent with the principle to not create what we do not need.
2023-03-02extra reductionsJSDurand
Finished the function of performing extra reductions. Still untested though.
2023-02-28Add a type Reducer for recording extra reductionsJSDurand
In the chain-rule machine, we need to skip through edges whose labels are "accepting", otherwise the time complexity will be high even for simple grammars. This implies that we will skip some "jumping up" in the item derivation forest. So we need to record these extra jumping up, in order to jump up at a later point. This Reducer type plays this role. But I still need more experiments to see if this approach works out as I intended.
2023-02-28Merge from masterJSDurand
2023-02-28Add no_item parameter.JSDurand
* chain/src/default.rs: * chain/src/lib.rs: Add a parameter that controls whether or not the chain-rule machine computes the item derivation forest as well. Sometimes we only need to recognize whether an input belongs to the grammar, but do not care about the derivations. This parameter can speed up the machine in that case.
2023-02-28default: add a planJSDurand
* chain/src/default.rs: Add a plan to fix things.
2023-02-27before a major refactorJSDurand
I decide to adopt a new approach of recording and updating item derivation forests. Since this affects a lot of things, I decide to commit before the refactor, so that I can create a branch for that refactor.
2023-02-13Fix phantom edgesJSDurand
Previously there was a minor bug: if the chain-rule machine ended in a node without children, which node should be accepting because of edges that have no children and hence were ignored, then since the node has no children, it would be regarded as not accepting. Now this issue is fixed by introducting real or imaginary edges, where an imaginary edge is used to determine the acceptance of nodes without chidlren.
2023-02-12Added the functionality of split or clone.JSDurand
I need more than the ability to clone nodes: I also need to split the nodes. Now this seems to be correctly added.
2023-02-03Finally produced the first correct forestJSDurand
Finally the prototype parser has produced the first correct forest. It is my first time to generate a correct forest, in fact, ever since the beginning of this project.
2023-01-28a prototype of an item derivation forestJSDurand
It seems to be complete now, but still awaits more tests to see where the errors are, which should be plenty, haha.
2023-01-22forest: clone correctlyJSDurand
Now the forest can detect if a node is packed or cloned, and correctly clones a node in those circumstances. But it still needs to be tested.
2023-01-20minor refactoringJSDurand
It seems the performance is indeed linear for a simple grammar. This is such a historical moment, for me, that I think it deserves a separate commit, haha.
2023-01-20chain: a prototype is added.JSDurand
I have an ostensibly working prototype now. Further tests are needed to make sure that the algorithm meets the time complexity requirement, though.
2023-01-03structural change: separate crates outJSDurand
I put functionalities that are not strictly core to separate crates, so that the whole package becomes more modular, and makes it easier to try other parsing algorithms in the future. Also I have to figure the forests out before finishing the core chain-rule algorithm, as the part about forests affects the labels of the grammars directly. From my experiences in writing the previous version, it is asking for trouble to change the labels type dramatically at a later point: too many places need to be changed. Thus I decide to figure the rough part of forests out. Actually I only have to figure out how to attach forests fragments to edges of the underlying atomic languages, and the more complex parts of putting forests together can be left to the recorders, which is my vision of assembling semi-ring values during the chain-rule machine. It should be relatively easy to produce forests fragments from grammars since we are just trying to extract some information from the grammar, not to manipulate those information in some complicated way. We have to do some manipulations in the process, though, in order to make sure that the nulling and epsilon-removal processes do not invalidate these fragments.