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In computer science, a chart parser is a type of parsing suitable for ambiguous grammars (including grammars of ). It uses the dynamic programming approach—partial hypothesized results are stored in a structure called a chart and can be re-used. This eliminates backtracking and prevents a combinatorial explosion.
Chart parsing is generally credited to Martin Kay.
Chart parsers can also be used for parsing computer languages. Earley parsers in particular have been used in compiler-compilers where their ability to parse using arbitrary Context-free grammars eases the task of writing the grammar for a particular language. However their lower efficiency has led to people avoiding them for most compiler work.
In bidirectional chart parsing, edges of the chart are marked with a direction, either forwards or backwards, and rules are enforced on the direction in which edges must point in order to be combined into further edges.
In incremental chart parsing, the chart is constructed incrementally as the text is edited by the user, with each change to the text resulting in the minimal possible corresponding change to the chart.
Chart parsers are distinguished between top-down parsing and bottom-up, as well as active and passive.
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