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| choice_points [2020/10/08 12:17] – revusky | choice_points [2020/10/27 18:12] – revusky | ||
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| I think the simplest way to think about the above cases (for most people, anyway) is just in terms of their analogues in a procedural programming language. The first three cases are effectively binary choices, a choice between entering the expansion inside the parentheses and jumping directly to what follows it. In all of these cases, the expansion within the parentheses is a choice point. The last case is a choice between n options and each of those n sub-expansions is a choice point in the grammar. | I think the simplest way to think about the above cases (for most people, anyway) is just in terms of their analogues in a procedural programming language. The first three cases are effectively binary choices, a choice between entering the expansion inside the parentheses and jumping directly to what follows it. In all of these cases, the expansion within the parentheses is a choice point. The last case is a choice between n options and each of those n sub-expansions is a choice point in the grammar. | ||
| - | ==== Zero Or More ==== | + | ==== Zero Or One ==== |
| - | A //zero-or-more// is a single (non-looping) choice. If the enclosed expansion matches, we enter it, and if not, we jump directly to whatever follows it. So, if we write: | + | A //zero-or-one// is a single (non-looping) choice. If the enclosed expansion matches, we enter it, and if not, we jump directly to whatever follows it. So, if we write: |
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