AST-based mathematical expression calculation algorithm

Abstract

The invention provides an AST-based mathematical expression calculation algorithm. The AST-based mathematical expression calculation algorithm comprises the following steps of 1, converting an expression input by a user into Token and identifying the Token, wherein the input is a user expression, and the output is Token, 2, forming an AST syntax tree by the Token identified in the previous step, wherein the input is Token, and the output is the AST syntax tree, and 3, analyzing the AST syntax tree to calculate the value of the expression, wherein the input is the AST syntax tree, and the output is the value of the expression. The algorithm has the following beneficial effects that 1, whether the input is legal or not can be checked when a user inputs the expression containing the identifier; and 2, if the built-in mathematical function cannot meet the requirements of the user, a self-defined function calling calculation function is also provided, that is, calling of the function defined by the user is supported, and the function of calculating the expression is greatly expanded; and 3, expression statements can be processed, and calculation formulas can be selected according to conditions, so that a user does not have any learning cost during use.

Description

technical field [0001] The invention belongs to the technical field of computing, and relates to a mathematical expression, in particular to an AST-based mathematical expression calculation algorithm. Background technique [0002] Reinforcement calculation requires a large number of calculation formulas; it is difficult for users to verify the correctness of the formula when they input it, and the user can only be prompted to modify a certain formula when it is called. Because there are many nodes and the formula is messy, users use it It is not convenient, so it has become an urgent problem to solve whether the verification formula is correct when the user inputs. [0003] The current commonly used formula calculation method: [0004] 1. Scan the entire suffix expression sequentially from left to right; [0005] 2. If it is an operand, push the operand onto the stack; [0006] 3. If it is an operator, pop the corresponding operand from the stack, pay attention to the ord...

AI Technical Summary

Problems solved by technology

[0009] The main disadvantage of the prior art is that it cannot handle unary operators and relational expression sentences: for example: d>20, h=20*d; d<=20, h=300; when the steel bar diameter is greater than 20, h takes The value of 20*diameter, when d is not greater than, h is 300; this kind of expression statement can be found everywhere in the steel bar specification atlas

The traditional calculation based on suffix expressions cannot realize the calculation of two meanings of a character

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