Snobol4 语言 实战 文本中化学分子式识别

Snobol4^【1】 语言实战：文本中化学分子式^【2】识别

化学分子式是化学领域中的基本表达方式，它描述了分子中原子种类和数量的信息。在文本处理^【3】和化学信息学中，识别和解析化学分子式是一项重要的任务。Snobol4 是一种古老的编程语言，以其简洁和强大的文本处理能力而闻名。本文将探讨如何使用 Snobol4 语言实现文本中化学分子式的识别。

Snobol4 简介

Snobol4 是一种高级编程语言，由David J. Farber、Ralph E. Griswold 和 Ivan P. Polonsky 在1962年设计。它特别适合于文本处理任务，如模式匹配^【4】、字符串操作^【5】和文本分析。Snobol4 的语法简洁，易于理解，这使得它在文本处理领域有着广泛的应用。

化学分子式识别的挑战

化学分子式通常包含字母和数字，如H2O、C6H12O6等。识别这些分子式需要处理以下挑战：

1. 字符识别^【6】：识别分子式中的字母和数字。
2. 结构解析^【7】：解析分子式中的原子和它们之间的关系。
3. 上下文理解^【8】：理解分子式在文本中的上下文，以避免错误匹配。

Snobol4 实现化学分子式识别

以下是一个使用 Snobol4 语言实现的化学分子式识别的示例代码。该代码旨在识别简单的分子式，如H2O、CO2等。

```snobol
:begin
input
|'H' 'He' 'Li' 'Be' 'B' 'C' 'N' 'O' 'F' 'Ne' 'Na' 'Mg' 'Al' 'Si' 'P' 'S' 'Cl' 'Ar' 'K' 'Ca' 'Sc' 'Ti' 'V' 'Cr' 'Mn' 'Fe' 'Co' 'Ni' 'Cu' 'Zn' 'Ga' 'Ge' 'As' 'Se' 'Br' 'Kr' 'Rb' 'Sr' 'Y' 'Zr' 'Nb' 'Mo' 'Tc' 'Ru' 'Rh' 'Pd' 'Ag' 'Cd' 'In' 'Sn' 'Sb' 'Te' 'I' 'Xe' 'Cs' 'Ba' 'La' 'Ce' 'Pr' 'Nd' 'Pm' 'Sm' 'Eu' 'Gd' 'Tb' 'Dy' 'Ho' 'Er' 'Tm' 'Yb' 'Lu' 'Hf' 'Ta' 'W' 'Re' 'Os' 'Ir' 'Pt' 'Au' 'Hg' 'Tl' 'Pb' 'Bi' 'Po' 'At' 'Rn' 'Fr' 'Ra' 'Ac' 'Th' 'Pa' 'U' 'Np' 'Pu' 'Am' 'Cm' 'Bk' 'Cf' 'Es' 'Fm' 'Md' 'No' 'Lr' 'Rf' 'Db' 'Sg' 'Bh' 'Hs' 'Mt' 'Ds' 'Rg' 'Cn' 'Nh' 'Fl' 'Mc' 'Lv' 'Ts' 'Og' ' '0' '1' '2' '3' '4' '5' '6' '7' '8' '9'|
|'H2' 'H3' 'H4' 'H5' 'H6' 'H7' 'H8' 'H9' 'He2' 'He3' 'He4' 'He5' 'He6' 'He7' 'He8' 'He9' 'Li2' 'Li3' 'Li4' 'Li5' 'Li6' 'Li7' 'Li8' 'Li9' 'Be2' 'Be3' 'Be4' 'Be5' 'Be6' 'Be7' 'Be8' 'Be9' 'B2' 'B3' 'B4' 'B5' 'B6' 'B7' 'B8' 'B9' 'C2' 'C3' 'C4' 'C5' 'C6' 'C7' 'C8' 'C9' 'N2' 'N3' 'N4' 'N5' 'N6' 'N7' 'N8' 'N9' 'O2' 'O3' 'O4' 'O5' 'O6' 'O7' 'O8' 'O9' 'F2' 'F3' 'F4' 'F5' 'F6' 'F7' 'F8' 'F9' 'Ne2' 'Ne3' 'Ne4' 'Ne5' 'Ne6' 'Ne7' 'Ne8' 'Ne9' 'Na2' 'Na3' 'Na4' 'Na5' 'Na6' 'Na7' 'Na8' 'Na9' 'Mg2' 'Mg3' 'Mg4' 'Mg5' 'Mg6' 'Mg7' 'Mg8' 'Mg9' 'Al2' 'Al3' 'Al4' 'Al5' 'Al6' 'Al7' 'Al8' 'Al9' 'Si2' 'Si3' 'Si4' 'Si5' 'Si6' 'Si7' 'Si8' 'Si9' 'P2' 'P3' 'P4' 'P5' 'P6' 'P7' 'P8' 'P9' 'S2' 'S3' 'S4' 'S5' 'S6' 'S7' 'S8' 'S9' 'Cl2' 'Cl3' 'Cl4' 'Cl5' 'Cl6' 'Cl7' 'Cl8' 'Cl9' 'Ar2' 'Ar3' 'Ar4' 'Ar5' 'Ar6' 'Ar7' 'Ar8' 'Ar9' 'K2' 'K3' 'K4' 'K5' 'K6' 'K7' 'K8' 'K9' 'Ca2' 'Ca3' 'Ca4' 'Ca5' 'Ca6' 'Ca7' 'Ca8' 'Ca9' 'Sc2' 'Sc3' 'Sc4' 'Sc5' 'Sc6' 'Sc7' 'Sc8' 'Sc9' 'Ti2' 'Ti3' 'Ti4' 'Ti5' 'Ti6' 'Ti7' 'Ti8' 'Ti9' 'V2' 'V3' 'V4' 'V5' 'V6' 'V7' 'V8' 'V9' 'Cr2' 'Cr3' 'Cr4' 'Cr5' 'Cr6' 'Cr7' 'Cr8' 'Cr9' 'Mn2' 'Mn3' 'Mn4' 'Mn5' 'Mn6' 'Mn7' 'Mn8' 'Mn9' 'Fe2' 'Fe3' 'Fe4' 'Fe5' 'Fe6' 'Fe7' 'Fe8' 'Fe9' 'Co2' 'Co3' 'Co4' 'Co5' 'Co6' 'Co7' 'Co8' 'Co9' 'Ni2' 'Ni3' 'Ni4' 'Ni5' 'Ni6' 'Ni7' 'Ni8' 'Ni9' 'Cu2' 'Cu3' 'Cu4' 'Cu5' 'Cu6' 'Cu7' 'Cu8' 'Cu9' 'Zn2' 'Zn3' 'Zn4' 'Zn5' 'Zn6' 'Zn7' 'Zn8' 'Zn9' 'Ga2' 'Ga3' 'Ga4' 'Ga5' 'Ga6' 'Ga7' 'Ga8' 'Ga9' 'Ge2' 'Ge3' 'Ge4' 'Ge5' 'Ge6' 'Ge7' 'Ge8' 'Ge9' 'As2' 'As3' 'As4' 'As5' 'As6' 'As7' 'As8' 'As9' 'Se2' 'Se3' 'Se4' 'Se5' 'Se6' 'Se7' 'Se8' 'Se9' 'Br2' 'Br3' 'Br4' 'Br5' 'Br6' 'Br7' 'Br8' 'Br9' 'Kr2' 'Kr3' 'Kr4' 'Kr5' 'Kr6' 'Kr7' 'Kr8' 'Kr9' 'Rb2' 'Rb3' 'Rb4' 'Rb5' 'Rb6' 'Rb7' 'Rb8' 'Rb9' 'Sr2' 'Sr3' 'Sr4' 'Sr5' 'Sr6' 'Sr7' 'Sr8' 'Sr9' 'Y2' 'Y3' 'Y4' 'Y5' 'Y6' 'Y7' 'Y8' 'Y9' 'Zr2' 'Zr3' 'Zr4' 'Zr5' 'Zr6' 'Zr7' 'Zr8' 'Zr9' 'Nb2' 'Nb3' 'Nb4' 'Nb5' 'Nb6' 'Nb7' 'Nb8' 'Nb9' 'Mo2' 'Mo3' 'Mo4' 'Mo5' 'Mo6' 'Mo7' 'Mo8' 'Mo9' 'Tc2' 'Tc3' 'Tc4' 'Tc5' 'Tc6' 'Tc7' 'Tc8' 'Tc9' 'Ru2' 'Ru3' 'Ru4' 'Ru5' 'Ru6' 'Ru7' 'Ru8' 'Ru9' 'Rh2' 'Rh3' 'Rh4' 'Rh5' 'Rh6' 'Rh7' 'Rh8' 'Rh9' 'Pd2' 'Pd3' 'Pd4' 'Pd5' 'Pd6' 'Pd7' 'Pd8' 'Pd9' 'Ag2' 'Ag3' 'Ag4' 'Ag5' 'Ag6' 'Ag7' 'Ag8' 'Ag9' 'Cd2' 'Cd3' 'Cd4' 'Cd5' 'Cd6' 'Cd7' 'Cd8' 'Cd9' 'In2' 'In3' 'In4' 'In5' 'In6' 'In7' 'In8' 'In9' 'Sn2' 'Sn3' 'Sn4' 'Sn5' 'Sn6' 'Sn7' 'Sn8' 'Sn9' 'Sb2' 'Sb3' 'Sb4' 'Sb5' 'Sb6' 'Sb7' 'Sb8' 'Sb9' 'Te2' 'Te3' 'Te4' 'Te5' 'Te6' 'Te7' 'Te8' 'Te9' 'I2' 'I3' 'I4' 'I5' 'I6' 'I7' 'I8' 'I9' 'Xe2' 'Xe3' 'Xe4' 'Xe5' 'Xe6' 'Xe7' 'Xe8' 'Xe9' 'Cs2' 'Cs3' 'Cs4' 'Cs5' 'Cs6' 'Cs7' 'Cs8' 'Cs9' 'Ba2' 'Ba3' 'Ba4' 'Ba5' 'Ba6' 'Ba7' 'Ba8' 'Ba9' 'La2' 'La3' 'La4' 'La5' 'La6' 'La7' 'La8' 'La9' 'Ce2' 'Ce3' 'Ce4' 'Ce5' 'Ce6' 'Ce7' 'Ce8' 'Ce9' 'Pr2' 'Pr3' 'Pr4' 'Pr5' 'Pr6' 'Pr7' 'Pr8' 'Pr9' 'Nd2' 'Nd3' 'Nd4' 'Nd5' 'Nd6' 'Nd7' 'Nd8' 'Nd9' 'Pm2' 'Pm3' 'Pm4' 'Pm5' 'Pm6' 'Pm7' 'Pm8' 'Pm9' 'Sm2' 'Sm3' 'Sm4' 'Sm5' 'Sm6' 'Sm7' 'Sm8' 'Sm9' 'Eu2' 'Eu3' 'Eu4' 'Eu5' 'Eu6' 'Eu7' 'Eu8' 'Eu9' 'Gd2' 'Gd3' 'Gd4' 'Gd5' 'Gd6' 'Gd7' 'Gd8' 'Gd9' 'Tb2' 'Tb3' 'Tb4' 'Tb5' 'Tb6' 'Tb7' 'Tb8' 'Tb9' 'Dy2' 'Dy3' 'Dy4' 'Dy5' 'Dy6' 'Dy7' 'Dy8' 'Dy9' 'Ho2' 'Ho3' 'Ho4' 'Ho5' 'Ho6' 'Ho7' 'Ho8' 'Ho9' 'Er2' 'Er3' 'Er4' 'Er5' 'Er6' 'Er7' 'Er8' 'Er9' 'Tm2' 'Tm3' 'Tm4' 'Tm5' 'Tm6' 'Tm7' 'Tm8' 'Tm9' 'Yb2' 'Yb3' 'Yb4' 'Yb5' 'Yb6' 'Yb7' 'Yb8' 'Yb9' 'Lu2' 'Lu3' 'Lu4' 'Lu5' 'Lu6' 'Lu7' 'Lu8' 'Lu9' 'Hf2' 'Hf3' 'Hf4' 'Hf5' 'Hf6' 'Hf7' 'Hf8' 'Hf9' 'Ta2' 'Ta3' 'Ta4' 'Ta5' 'Ta6' 'Ta7' 'Ta8' 'Ta9' 'W2' 'W3' 'W4' 'W5' 'W6' 'W7' 'W8' 'W9' 'Re2' 'Re3' 'Re4' 'Re5' 'Re6' 'Re7' 'Re8' 'Re9' 'Os2' 'Os3' 'Os4' 'Os5' 'Os6' 'Os7' 'Os8' 'Os9' 'Ir2' 'Ir3' 'Ir4' 'Ir5' 'Ir6' 'Ir7' 'Ir8' 'Ir9' 'Pt2' 'Pt3' 'Pt4' 'Pt5' 'Pt6' 'Pt7' 'Pt8' 'Pt9' 'Au2' 'Au3' 'Au4' 'Au5' 'Au6' 'Au7' 'Au8' 'Au9' 'Hg2' 'Hg3' 'Hg4' 'Hg5' 'Hg6' 'Hg7' 'Hg8' 'Hg9' 'Tl2' 'Tl3' 'Tl4' 'Tl5' 'Tl6' 'Tl7' 'Tl8' 'Tl9' 'Pb2' 'Pb3' 'Pb4' 'Pb5' 'Pb6' 'Pb7' 'Pb8' 'Pb9' 'Bi2' 'Bi3' 'Bi4' 'Bi5' 'Bi6' 'Bi7' 'Bi8' 'Bi9' 'Po2' 'Po3' 'Po4' 'Po5' 'Po6' 'Po7' 'Po8' 'Po9' 'At2' 'At3' 'At4' 'At5' 'At6' 'At7' 'At8' 'At9' 'Rn2' 'Rn3' 'Rn4' 'Rn5' 'Rn6' 'Rn7' 'Rn8' 'Rn9' 'Fr2' 'Fr3' 'Fr4' 'Fr5' 'Fr6' 'Fr7' 'Fr8' 'Fr9' 'Ra2' 'Ra3' 'Ra4' 'Ra5' 'Ra6' 'Ra7' 'Ra8' 'Ra9' 'Ac2' 'Ac3' 'Ac4' 'Ac5' 'Ac6' 'Ac7' 'Ac8' 'Ac9' 'Th2' 'Th3' 'Th4' 'Th5' 'Th6' 'Th7' 'Th8' 'Th9' 'Pa2' 'Pa3' 'Pa4' 'Pa5' 'Pa6' 'Pa7' 'Pa8' 'Pa9' 'U2' 'U3' 'U4' 'U5' 'U6' 'U7' 'U8' 'U9' 'Np2' 'Np3' 'Np4' 'Np5' 'Np6' 'Np7' 'Np8' 'Np9' 'Pu2' 'Pu3' 'Pu4' 'Pu5' 'Pu6' 'Pu7' 'Pu8' 'Pu9' 'Am2' 'Am3' 'Am4' 'Am5' 'Am6' 'Am7' 'Am8' 'Am9' 'Cm2' 'Cm3' 'Cm4' 'Cm5' 'Cm6' 'Cm7' 'Cm8' 'Cm9' 'Bk2' 'Bk3' 'Bk4' 'Bk5' 'Bk6' 'Bk7' 'Bk8' 'Bk9' 'Cf2' 'Cf3' 'Cf4' 'Cf5' 'Cf6' 'Cf7' 'Cf8' 'Cf9' 'Es2' 'Es3' 'Es4' 'Es5' 'Es6' 'Es7' 'Es8' 'Es9' 'Fm2' '